diff --git a/pkg/front_end/lib/src/fasta/kernel/type_builder_computer.dart b/pkg/front_end/lib/src/fasta/kernel/type_builder_computer.dart
index 0aea072..28ac4f2 100644
--- a/pkg/front_end/lib/src/fasta/kernel/type_builder_computer.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/type_builder_computer.dart
@@ -155,7 +155,7 @@
     }
     for (int i = 0; i < namedParameters.length; i++) {
       NamedType parameter = namedParameters[i];
-      TypeBuilder type = positionalParameters[i].accept(this);
+      TypeBuilder type = parameter.type.accept(this);
       formals[i + positionalParameters.length] = new FormalParameterBuilder(
           null, 0, type, parameter.name, null, -1, null)
         ..kind = FormalParameterKind.optionalNamed;
diff --git a/pkg/front_end/testcases/general/flutter_issue68092/main.dart b/pkg/front_end/testcases/general/flutter_issue68092/main.dart
new file mode 100644
index 0000000..4ff4f3b
--- /dev/null
+++ b/pkg/front_end/testcases/general/flutter_issue68092/main.dart
@@ -0,0 +1,6 @@
+import 'main_lib.dart';
+
+void main() {
+  int f({int x}) => null;
+  Registry().register(f);
+}
diff --git a/pkg/front_end/testcases/general/flutter_issue68092/main.dart.outline.expect b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.outline.expect
new file mode 100644
index 0000000..cfc2e45
--- /dev/null
+++ b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.outline.expect
@@ -0,0 +1,32 @@
+library;
+import self as self;
+
+import "org-dartlang-testcase:///main_lib.dart";
+
+static method main() → void
+  ;
+
+library;
+import self as self2;
+import "dart:core" as core;
+
+class DynamicDispatchRegistry<T extends core::Function* = core::Function*> extends core::Object {
+  synthetic constructor •() → self2::DynamicDispatchRegistry<self2::DynamicDispatchRegistry::T*>*
+    ;
+  method register(generic-covariant-impl self2::DynamicDispatchRegistry::T* function) → self2::DynamicDispatchRegistry::T*
+    ;
+  abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
+  abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf
+  abstract member-signature method _simpleInstanceOf(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOf
+  abstract member-signature method _simpleInstanceOfTrue(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfTrue
+  abstract member-signature method _simpleInstanceOfFalse(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfFalse
+  abstract member-signature operator ==(dynamic other) → core::bool*; -> core::Object::==
+  abstract member-signature get hashCode() → core::int*; -> core::Object::hashCode
+  abstract member-signature method toString() → core::String*; -> core::Object::toString
+  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
+  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
+}
+class Registry extends self2::DynamicDispatchRegistry<({x: core::int*}) →* core::int*> {
+  synthetic constructor •() → self2::Registry*
+    ;
+}
diff --git a/pkg/front_end/testcases/general/flutter_issue68092/main.dart.strong.expect b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.strong.expect
new file mode 100644
index 0000000..317b261
--- /dev/null
+++ b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.strong.expect
@@ -0,0 +1,43 @@
+library;
+import self as self;
+import "dart:core" as core;
+import "main_lib.dart" as mai;
+
+import "org-dartlang-testcase:///main_lib.dart";
+
+static method main() → void {
+  function f({core::int* x = #C1}) → core::int*
+    return null;
+  new mai::Registry::•().{mai::DynamicDispatchRegistry::register}(f);
+}
+
+library;
+import self as mai;
+import "dart:core" as core;
+
+class DynamicDispatchRegistry<T extends core::Function* = core::Function*> extends core::Object {
+  synthetic constructor •() → mai::DynamicDispatchRegistry<mai::DynamicDispatchRegistry::T*>*
+    : super core::Object::•()
+    ;
+  method register(generic-covariant-impl mai::DynamicDispatchRegistry::T* function) → mai::DynamicDispatchRegistry::T*
+    return null;
+  abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
+  abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf
+  abstract member-signature method _simpleInstanceOf(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOf
+  abstract member-signature method _simpleInstanceOfTrue(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfTrue
+  abstract member-signature method _simpleInstanceOfFalse(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfFalse
+  abstract member-signature operator ==(dynamic other) → core::bool*; -> core::Object::==
+  abstract member-signature get hashCode() → core::int*; -> core::Object::hashCode
+  abstract member-signature method toString() → core::String*; -> core::Object::toString
+  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
+  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
+}
+class Registry extends mai::DynamicDispatchRegistry<({x: core::int*}) →* core::int*> {
+  synthetic constructor •() → mai::Registry*
+    : super mai::DynamicDispatchRegistry::•()
+    ;
+}
+
+constants  {
+  #C1 = null
+}
diff --git a/pkg/front_end/testcases/general/flutter_issue68092/main.dart.strong.transformed.expect b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.strong.transformed.expect
new file mode 100644
index 0000000..317b261
--- /dev/null
+++ b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.strong.transformed.expect
@@ -0,0 +1,43 @@
+library;
+import self as self;
+import "dart:core" as core;
+import "main_lib.dart" as mai;
+
+import "org-dartlang-testcase:///main_lib.dart";
+
+static method main() → void {
+  function f({core::int* x = #C1}) → core::int*
+    return null;
+  new mai::Registry::•().{mai::DynamicDispatchRegistry::register}(f);
+}
+
+library;
+import self as mai;
+import "dart:core" as core;
+
+class DynamicDispatchRegistry<T extends core::Function* = core::Function*> extends core::Object {
+  synthetic constructor •() → mai::DynamicDispatchRegistry<mai::DynamicDispatchRegistry::T*>*
+    : super core::Object::•()
+    ;
+  method register(generic-covariant-impl mai::DynamicDispatchRegistry::T* function) → mai::DynamicDispatchRegistry::T*
+    return null;
+  abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
+  abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf
+  abstract member-signature method _simpleInstanceOf(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOf
+  abstract member-signature method _simpleInstanceOfTrue(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfTrue
+  abstract member-signature method _simpleInstanceOfFalse(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfFalse
+  abstract member-signature operator ==(dynamic other) → core::bool*; -> core::Object::==
+  abstract member-signature get hashCode() → core::int*; -> core::Object::hashCode
+  abstract member-signature method toString() → core::String*; -> core::Object::toString
+  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
+  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
+}
+class Registry extends mai::DynamicDispatchRegistry<({x: core::int*}) →* core::int*> {
+  synthetic constructor •() → mai::Registry*
+    : super mai::DynamicDispatchRegistry::•()
+    ;
+}
+
+constants  {
+  #C1 = null
+}
diff --git a/pkg/front_end/testcases/general/flutter_issue68092/main.dart.textual_outline.expect b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.textual_outline.expect
new file mode 100644
index 0000000..3e55fb8
--- /dev/null
+++ b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.textual_outline.expect
@@ -0,0 +1,3 @@
+import 'main_lib.dart';
+
+void main() {}
diff --git a/pkg/front_end/testcases/general/flutter_issue68092/main.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.textual_outline_modelled.expect
new file mode 100644
index 0000000..3e55fb8
--- /dev/null
+++ b/pkg/front_end/testcases/general/flutter_issue68092/main.dart.textual_outline_modelled.expect
@@ -0,0 +1,3 @@
+import 'main_lib.dart';
+
+void main() {}
diff --git a/pkg/front_end/testcases/general/flutter_issue68092/main_lib.dart b/pkg/front_end/testcases/general/flutter_issue68092/main_lib.dart
new file mode 100644
index 0000000..e43e181
--- /dev/null
+++ b/pkg/front_end/testcases/general/flutter_issue68092/main_lib.dart
@@ -0,0 +1,5 @@
+class DynamicDispatchRegistry<T extends Function> {
+  T register(T function) => null;
+}
+
+class Registry extends DynamicDispatchRegistry<int Function({int x})> {}
diff --git a/pkg/front_end/testcases/general/flutter_issue68092/test.options b/pkg/front_end/testcases/general/flutter_issue68092/test.options
new file mode 100644
index 0000000..bfe6dc8
--- /dev/null
+++ b/pkg/front_end/testcases/general/flutter_issue68092/test.options
@@ -0,0 +1 @@
+main_lib.dart
\ No newline at end of file
diff --git a/runtime/tests/vm/dart/flutter_regression67803_test.dart b/runtime/tests/vm/dart/flutter_regression67803_test.dart
new file mode 100644
index 0000000..71abd70
--- /dev/null
+++ b/runtime/tests/vm/dart/flutter_regression67803_test.dart
@@ -0,0 +1,372 @@
+// 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:expect/expect.dart';
+
+final bool kTrue = int.parse('1') == 1;
+
+main() {
+  // Ensure fields are not inferred to be constants and ensure we use all fields
+  // (to avoid them being tree shaken).
+  final useAllFields = (kTrue ? foo : foo2).toString();
+  for (int i = 0; i <= 64; ++i) {
+    Expect.isTrue(useAllFields.contains('$i'));
+  }
+
+  // Ensure calling dyn:get:field64 returns the right value.
+  Expect.equals(64, ((kTrue ? foo : Baz(10)) as dynamic).field64);
+
+  // Ensure calling get:field64 returns the right value.
+  Expect.equals(64, (kTrue ? foo : Bar(10)).field64);
+
+  // Ensure potentially inlined, direct field load yield right value.
+  Expect.equals(64, (kTrue ? foo : foo2).field64);
+}
+
+final foo = Foo(
+    0,
+    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,
+    41,
+    42,
+    43,
+    44,
+    45,
+    46,
+    47,
+    48,
+    49,
+    50,
+    51,
+    52,
+    53,
+    54,
+    55,
+    56,
+    57,
+    58,
+    59,
+    60,
+    61,
+    62,
+    63,
+    64);
+
+final foo2 = Foo(
+    2 * 0,
+    2 * 1,
+    2 * 2,
+    2 * 3,
+    2 * 4,
+    2 * 5,
+    2 * 6,
+    2 * 7,
+    2 * 8,
+    2 * 9,
+    2 * 10,
+    2 * 11,
+    2 * 12,
+    2 * 13,
+    2 * 14,
+    2 * 15,
+    2 * 16,
+    2 * 17,
+    2 * 18,
+    2 * 19,
+    2 * 20,
+    2 * 21,
+    2 * 22,
+    2 * 23,
+    2 * 24,
+    2 * 25,
+    2 * 26,
+    2 * 27,
+    2 * 28,
+    2 * 29,
+    2 * 30,
+    2 * 31,
+    2 * 32,
+    2 * 33,
+    2 * 34,
+    2 * 35,
+    2 * 36,
+    2 * 37,
+    2 * 38,
+    2 * 39,
+    2 * 40,
+    2 * 41,
+    2 * 42,
+    2 * 43,
+    2 * 44,
+    2 * 45,
+    2 * 46,
+    2 * 47,
+    2 * 48,
+    2 * 49,
+    2 * 50,
+    2 * 51,
+    2 * 52,
+    2 * 53,
+    2 * 54,
+    2 * 55,
+    2 * 56,
+    2 * 57,
+    2 * 58,
+    2 * 59,
+    2 * 60,
+    2 * 61,
+    2 * 62,
+    2 * 63,
+    2 * 64);
+
+class Bar {
+  final int field64;
+  Bar(this.field64);
+}
+
+class Baz {
+  final int field64;
+  Baz(this.field64);
+}
+
+class Foo implements Bar {
+  final int field0;
+  final int field1;
+  final int field2;
+  final int field3;
+  final int field4;
+  final int field5;
+  final int field6;
+  final int field7;
+  final int field8;
+  final int field9;
+  final int field10;
+  final int field11;
+  final int field12;
+  final int field13;
+  final int field14;
+  final int field15;
+  final int field16;
+  final int field17;
+  final int field18;
+  final int field19;
+  final int field20;
+  final int field21;
+  final int field22;
+  final int field23;
+  final int field24;
+  final int field25;
+  final int field26;
+  final int field27;
+  final int field28;
+  final int field29;
+  final int field30;
+  final int field31;
+  final int field32;
+  final int field33;
+  final int field34;
+  final int field35;
+  final int field36;
+  final int field37;
+  final int field38;
+  final int field39;
+  final int field40;
+  final int field41;
+  final int field42;
+  final int field43;
+  final int field44;
+  final int field45;
+  final int field46;
+  final int field47;
+  final int field48;
+  final int field49;
+  final int field50;
+  final int field51;
+  final int field52;
+  final int field53;
+  final int field54;
+  final int field55;
+  final int field56;
+  final int field57;
+  final int field58;
+  final int field59;
+  final int field60;
+  final int field61;
+  final int field62;
+  final int field63;
+  final int field64;
+
+  Foo(
+      this.field0,
+      this.field1,
+      this.field2,
+      this.field3,
+      this.field4,
+      this.field5,
+      this.field6,
+      this.field7,
+      this.field8,
+      this.field9,
+      this.field10,
+      this.field11,
+      this.field12,
+      this.field13,
+      this.field14,
+      this.field15,
+      this.field16,
+      this.field17,
+      this.field18,
+      this.field19,
+      this.field20,
+      this.field21,
+      this.field22,
+      this.field23,
+      this.field24,
+      this.field25,
+      this.field26,
+      this.field27,
+      this.field28,
+      this.field29,
+      this.field30,
+      this.field31,
+      this.field32,
+      this.field33,
+      this.field34,
+      this.field35,
+      this.field36,
+      this.field37,
+      this.field38,
+      this.field39,
+      this.field40,
+      this.field41,
+      this.field42,
+      this.field43,
+      this.field44,
+      this.field45,
+      this.field46,
+      this.field47,
+      this.field48,
+      this.field49,
+      this.field50,
+      this.field51,
+      this.field52,
+      this.field53,
+      this.field54,
+      this.field55,
+      this.field56,
+      this.field57,
+      this.field58,
+      this.field59,
+      this.field60,
+      this.field61,
+      this.field62,
+      this.field63,
+      this.field64);
+
+  toString() => '''
+     $field0;
+     $field1;
+     $field2;
+     $field3;
+     $field4;
+     $field5;
+     $field6;
+     $field7;
+     $field8;
+     $field9;
+    $field10;
+    $field11;
+    $field12;
+    $field13;
+    $field14;
+    $field15;
+    $field16;
+    $field17;
+    $field18;
+    $field19;
+    $field20;
+    $field21;
+    $field22;
+    $field23;
+    $field24;
+    $field25;
+    $field26;
+    $field27;
+    $field28;
+    $field29;
+    $field30;
+    $field31;
+    $field32;
+    $field33;
+    $field34;
+    $field35;
+    $field36;
+    $field37;
+    $field38;
+    $field39;
+    $field40;
+    $field41;
+    $field42;
+    $field43;
+    $field44;
+    $field45;
+    $field46;
+    $field47;
+    $field48;
+    $field49;
+    $field50;
+    $field51;
+    $field52;
+    $field53;
+    $field54;
+    $field55;
+    $field56;
+    $field57;
+    $field58;
+    $field59;
+    $field60;
+    $field61;
+    $field62;
+    $field63;
+    $field64;
+    ''';
+}
diff --git a/runtime/tests/vm/dart_2/flutter_regression67803_test.dart b/runtime/tests/vm/dart_2/flutter_regression67803_test.dart
new file mode 100644
index 0000000..71abd70
--- /dev/null
+++ b/runtime/tests/vm/dart_2/flutter_regression67803_test.dart
@@ -0,0 +1,372 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:expect/expect.dart';
+
+final bool kTrue = int.parse('1') == 1;
+
+main() {
+  // Ensure fields are not inferred to be constants and ensure we use all fields
+  // (to avoid them being tree shaken).
+  final useAllFields = (kTrue ? foo : foo2).toString();
+  for (int i = 0; i <= 64; ++i) {
+    Expect.isTrue(useAllFields.contains('$i'));
+  }
+
+  // Ensure calling dyn:get:field64 returns the right value.
+  Expect.equals(64, ((kTrue ? foo : Baz(10)) as dynamic).field64);
+
+  // Ensure calling get:field64 returns the right value.
+  Expect.equals(64, (kTrue ? foo : Bar(10)).field64);
+
+  // Ensure potentially inlined, direct field load yield right value.
+  Expect.equals(64, (kTrue ? foo : foo2).field64);
+}
+
+final foo = Foo(
+    0,
+    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,
+    41,
+    42,
+    43,
+    44,
+    45,
+    46,
+    47,
+    48,
+    49,
+    50,
+    51,
+    52,
+    53,
+    54,
+    55,
+    56,
+    57,
+    58,
+    59,
+    60,
+    61,
+    62,
+    63,
+    64);
+
+final foo2 = Foo(
+    2 * 0,
+    2 * 1,
+    2 * 2,
+    2 * 3,
+    2 * 4,
+    2 * 5,
+    2 * 6,
+    2 * 7,
+    2 * 8,
+    2 * 9,
+    2 * 10,
+    2 * 11,
+    2 * 12,
+    2 * 13,
+    2 * 14,
+    2 * 15,
+    2 * 16,
+    2 * 17,
+    2 * 18,
+    2 * 19,
+    2 * 20,
+    2 * 21,
+    2 * 22,
+    2 * 23,
+    2 * 24,
+    2 * 25,
+    2 * 26,
+    2 * 27,
+    2 * 28,
+    2 * 29,
+    2 * 30,
+    2 * 31,
+    2 * 32,
+    2 * 33,
+    2 * 34,
+    2 * 35,
+    2 * 36,
+    2 * 37,
+    2 * 38,
+    2 * 39,
+    2 * 40,
+    2 * 41,
+    2 * 42,
+    2 * 43,
+    2 * 44,
+    2 * 45,
+    2 * 46,
+    2 * 47,
+    2 * 48,
+    2 * 49,
+    2 * 50,
+    2 * 51,
+    2 * 52,
+    2 * 53,
+    2 * 54,
+    2 * 55,
+    2 * 56,
+    2 * 57,
+    2 * 58,
+    2 * 59,
+    2 * 60,
+    2 * 61,
+    2 * 62,
+    2 * 63,
+    2 * 64);
+
+class Bar {
+  final int field64;
+  Bar(this.field64);
+}
+
+class Baz {
+  final int field64;
+  Baz(this.field64);
+}
+
+class Foo implements Bar {
+  final int field0;
+  final int field1;
+  final int field2;
+  final int field3;
+  final int field4;
+  final int field5;
+  final int field6;
+  final int field7;
+  final int field8;
+  final int field9;
+  final int field10;
+  final int field11;
+  final int field12;
+  final int field13;
+  final int field14;
+  final int field15;
+  final int field16;
+  final int field17;
+  final int field18;
+  final int field19;
+  final int field20;
+  final int field21;
+  final int field22;
+  final int field23;
+  final int field24;
+  final int field25;
+  final int field26;
+  final int field27;
+  final int field28;
+  final int field29;
+  final int field30;
+  final int field31;
+  final int field32;
+  final int field33;
+  final int field34;
+  final int field35;
+  final int field36;
+  final int field37;
+  final int field38;
+  final int field39;
+  final int field40;
+  final int field41;
+  final int field42;
+  final int field43;
+  final int field44;
+  final int field45;
+  final int field46;
+  final int field47;
+  final int field48;
+  final int field49;
+  final int field50;
+  final int field51;
+  final int field52;
+  final int field53;
+  final int field54;
+  final int field55;
+  final int field56;
+  final int field57;
+  final int field58;
+  final int field59;
+  final int field60;
+  final int field61;
+  final int field62;
+  final int field63;
+  final int field64;
+
+  Foo(
+      this.field0,
+      this.field1,
+      this.field2,
+      this.field3,
+      this.field4,
+      this.field5,
+      this.field6,
+      this.field7,
+      this.field8,
+      this.field9,
+      this.field10,
+      this.field11,
+      this.field12,
+      this.field13,
+      this.field14,
+      this.field15,
+      this.field16,
+      this.field17,
+      this.field18,
+      this.field19,
+      this.field20,
+      this.field21,
+      this.field22,
+      this.field23,
+      this.field24,
+      this.field25,
+      this.field26,
+      this.field27,
+      this.field28,
+      this.field29,
+      this.field30,
+      this.field31,
+      this.field32,
+      this.field33,
+      this.field34,
+      this.field35,
+      this.field36,
+      this.field37,
+      this.field38,
+      this.field39,
+      this.field40,
+      this.field41,
+      this.field42,
+      this.field43,
+      this.field44,
+      this.field45,
+      this.field46,
+      this.field47,
+      this.field48,
+      this.field49,
+      this.field50,
+      this.field51,
+      this.field52,
+      this.field53,
+      this.field54,
+      this.field55,
+      this.field56,
+      this.field57,
+      this.field58,
+      this.field59,
+      this.field60,
+      this.field61,
+      this.field62,
+      this.field63,
+      this.field64);
+
+  toString() => '''
+     $field0;
+     $field1;
+     $field2;
+     $field3;
+     $field4;
+     $field5;
+     $field6;
+     $field7;
+     $field8;
+     $field9;
+    $field10;
+    $field11;
+    $field12;
+    $field13;
+    $field14;
+    $field15;
+    $field16;
+    $field17;
+    $field18;
+    $field19;
+    $field20;
+    $field21;
+    $field22;
+    $field23;
+    $field24;
+    $field25;
+    $field26;
+    $field27;
+    $field28;
+    $field29;
+    $field30;
+    $field31;
+    $field32;
+    $field33;
+    $field34;
+    $field35;
+    $field36;
+    $field37;
+    $field38;
+    $field39;
+    $field40;
+    $field41;
+    $field42;
+    $field43;
+    $field44;
+    $field45;
+    $field46;
+    $field47;
+    $field48;
+    $field49;
+    $field50;
+    $field51;
+    $field52;
+    $field53;
+    $field54;
+    $field55;
+    $field56;
+    $field57;
+    $field58;
+    $field59;
+    $field60;
+    $field61;
+    $field62;
+    $field63;
+    $field64;
+    ''';
+}
diff --git a/runtime/vm/compiler/backend/flow_graph.cc b/runtime/vm/compiler/backend/flow_graph.cc
index 82430b4..dc5b713 100644
--- a/runtime/vm/compiler/backend/flow_graph.cc
+++ b/runtime/vm/compiler/backend/flow_graph.cc
@@ -128,6 +128,20 @@
   }
 }
 
+Representation FlowGraph::UnboxedFieldRepresentationOf(const Field& field) {
+  switch (field.UnboxedFieldCid()) {
+    case kDoubleCid:
+      return kUnboxedDouble;
+    case kFloat32x4Cid:
+      return kUnboxedFloat32x4;
+    case kFloat64x2Cid:
+      return kUnboxedFloat64x2;
+    default:
+      RELEASE_ASSERT(field.is_non_nullable_integer());
+      return kUnboxedInt64;
+  }
+}
+
 void FlowGraph::ReplaceCurrentInstruction(ForwardInstructionIterator* iterator,
                                           Instruction* current,
                                           Instruction* replacement) {
diff --git a/runtime/vm/compiler/backend/flow_graph.h b/runtime/vm/compiler/backend/flow_graph.h
index bac38c8..50ea5ec 100644
--- a/runtime/vm/compiler/backend/flow_graph.h
+++ b/runtime/vm/compiler/backend/flow_graph.h
@@ -147,6 +147,8 @@
 
   static Representation ReturnRepresentationOf(const Function& function);
 
+  static Representation UnboxedFieldRepresentationOf(const Field& field);
+
   // The number of variables (or boxes) inside the functions frame - meaning
   // below the frame pointer.  This does not include the expression stack.
   intptr_t num_stack_locals() const {
diff --git a/runtime/vm/compiler/backend/il.cc b/runtime/vm/compiler/backend/il.cc
index cf1fd3a..689ef3d 100644
--- a/runtime/vm/compiler/backend/il.cc
+++ b/runtime/vm/compiler/backend/il.cc
@@ -1032,21 +1032,7 @@
   ASSERT((index == 0) || (index == 1));
   if ((index == 1) && IsUnboxedStore()) {
     const Field& field = slot().field();
-    const intptr_t cid = field.UnboxedFieldCid();
-    switch (cid) {
-      case kDoubleCid:
-        return kUnboxedDouble;
-      case kFloat32x4Cid:
-        return kUnboxedFloat32x4;
-      case kFloat64x2Cid:
-        return kUnboxedFloat64x2;
-      default:
-        if (field.is_non_nullable_integer()) {
-          return kUnboxedInt64;
-        } else {
-          UNREACHABLE();
-        }
-    }
+    return FlowGraph::UnboxedFieldRepresentationOf(field);
   }
   return kTagged;
 }
diff --git a/runtime/vm/compiler/graph_intrinsifier.cc b/runtime/vm/compiler/graph_intrinsifier.cc
index 3f77aa2..9b38d1d 100644
--- a/runtime/vm/compiler/graph_intrinsifier.cc
+++ b/runtime/vm/compiler/graph_intrinsifier.cc
@@ -1102,8 +1102,23 @@
   BlockBuilder builder(flow_graph, normal_entry);
 
   auto receiver = builder.AddParameter(0, /*with_frame=*/false);
-  auto field_value = builder.AddDefinition(new (zone) LoadFieldInstr(
+  Definition* field_value = builder.AddDefinition(new (zone) LoadFieldInstr(
       new (zone) Value(receiver), slot, builder.TokenPos()));
+
+  // We only support cases where we do not have to create a box (whose
+  // allocation could fail).
+  ASSERT(function.HasUnboxedReturnValue() ||
+         !FlowGraphCompiler::IsUnboxedField(field));
+
+  // We might need to unbox the field value before returning.
+  if (function.HasUnboxedReturnValue() &&
+      !FlowGraphCompiler::IsUnboxedField(field)) {
+    ASSERT(FLAG_precompiled_mode);
+    field_value = builder.AddUnboxInstr(
+        FlowGraph::ReturnRepresentationOf(flow_graph->function()),
+        new Value(field_value), /*is_checked=*/true);
+  }
+
   builder.AddReturn(new (zone) Value(field_value));
   return true;
 }
@@ -1142,25 +1157,9 @@
     // We do not support storing to possibly guarded fields in JIT in graph
     // intrinsics.
     ASSERT(FLAG_precompiled_mode);
-
-    Representation representation = kNoRepresentation;
-    switch (field.guarded_cid()) {
-      case kDoubleCid:
-        representation = kUnboxedDouble;
-        break;
-      case kFloat32x4Cid:
-        representation = kUnboxedFloat32x4;
-        break;
-      case kFloat64x2Cid:
-        representation = kUnboxedFloat64x2;
-        break;
-      default:
-        ASSERT(field.is_non_nullable_integer());
-        representation = kUnboxedInt64;
-        break;
-    }
-    value = builder.AddUnboxInstr(representation, new Value(value),
-                                  /*is_checked=*/true);
+    value = builder.AddUnboxInstr(
+        FlowGraph::UnboxedFieldRepresentationOf(field), new Value(value),
+        /*is_checked=*/true);
   }
 
   builder.AddInstruction(new (zone) StoreInstanceFieldInstr(
diff --git a/runtime/vm/compiler/intrinsifier.cc b/runtime/vm/compiler/intrinsifier.cc
index a1f21f1..35ade83 100644
--- a/runtime/vm/compiler/intrinsifier.cc
+++ b/runtime/vm/compiler/intrinsifier.cc
@@ -113,9 +113,9 @@
         return false;
       }
     } else {
-      // If the field is boxed, then the getter cannot return an unboxed value
-      // either (if it could, we would know the field itself can be unboxed).
-      RELEASE_ASSERT(!function.HasUnboxedReturnValue());
+      // If the field is boxed, then we can either return the box directly or
+      // unbox it and return unboxed representation.
+      return true;
     }
   } else {
     ASSERT(is_setter);
diff --git a/runtime/vm/compiler/write_barrier_elimination.cc b/runtime/vm/compiler/write_barrier_elimination.cc
index 10b18c5..efc79e8 100644
--- a/runtime/vm/compiler/write_barrier_elimination.cc
+++ b/runtime/vm/compiler/write_barrier_elimination.cc
@@ -192,6 +192,8 @@
 void WriteBarrierElimination::IndexDefinitions(Zone* zone) {
   BitmapBuilder array_allocations;
 
+  GrowableArray<Definition*> create_array_worklist;
+
   for (intptr_t i = 0; i < block_order_->length(); ++i) {
     BlockEntryInstr* const block = block_order_->At(i);
     if (auto join_block = block->AsJoinEntry()) {
@@ -209,8 +211,12 @@
     for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
       if (Definition* current = it.Current()->AsDefinition()) {
         if (IsUsable(current)) {
-          array_allocations.Set(definition_count_, current->IsCreateArray());
+          const bool is_create_array = current->IsCreateArray();
+          array_allocations.Set(definition_count_, is_create_array);
           definition_indices_.Insert({current, definition_count_++});
+          if (is_create_array) {
+            create_array_worklist.Add(current);
+          }
 #if defined(DEBUG)
           if (tracing_) {
             THR_Print("Definition (%" Pd ") has index %" Pd ".\n",
@@ -222,6 +228,20 @@
     }
   }
 
+  while (!create_array_worklist.is_empty()) {
+    auto instr = create_array_worklist.RemoveLast();
+    for (Value::Iterator it(instr->input_use_list()); !it.Done();
+         it.Advance()) {
+      if (auto phi_use = it.Current()->instruction()->AsPhi()) {
+        const intptr_t index = Index(phi_use);
+        if (!array_allocations.Get(index)) {
+          array_allocations.Set(index, /*can_be_create_array=*/true);
+          create_array_worklist.Add(phi_use);
+        }
+      }
+    }
+  }
+
   vector_ = new (zone) BitVector(zone, definition_count_);
   vector_->SetAll();
   array_allocations_mask_ = new (zone) BitVector(zone, definition_count_);
diff --git a/runtime/vm/compiler/write_barrier_elimination_test.cc b/runtime/vm/compiler/write_barrier_elimination_test.cc
index 88d4e7c..b86e827 100644
--- a/runtime/vm/compiler/write_barrier_elimination_test.cc
+++ b/runtime/vm/compiler/write_barrier_elimination_test.cc
@@ -12,7 +12,8 @@
 DEBUG_ONLY(DECLARE_FLAG(bool, trace_write_barrier_elimination);)
 
 ISOLATE_UNIT_TEST_CASE(IRTest_WriteBarrierElimination_JoinSuccessors) {
-  DEBUG_ONLY(FLAG_trace_write_barrier_elimination = true);
+  DEBUG_ONLY(
+      SetFlagScope<bool> sfs(&FLAG_trace_write_barrier_elimination, true));
   const char* nullable_tag = TestCase::NullableTag();
   const char* null_assert_tag = TestCase::NullAssertTag();
 
@@ -82,7 +83,8 @@
 }
 
 ISOLATE_UNIT_TEST_CASE(IRTest_WriteBarrierElimination_AtLeastOnce) {
-  DEBUG_ONLY(FLAG_trace_write_barrier_elimination = true);
+  DEBUG_ONLY(
+      SetFlagScope<bool> sfs(&FLAG_trace_write_barrier_elimination, true));
   // Ensure that we process every block at least once during the analysis
   // phase so that the out-sets will be initialized. If we don't process
   // each block at least once, the store "c.next = n" will be marked
@@ -137,7 +139,8 @@
 }
 
 ISOLATE_UNIT_TEST_CASE(IRTest_WriteBarrierElimination_Arrays) {
-  DEBUG_ONLY(FLAG_trace_write_barrier_elimination = true);
+  DEBUG_ONLY(
+      SetFlagScope<bool> sfs(&FLAG_trace_write_barrier_elimination, true));
   const char* nullable_tag = TestCase::NullableTag();
 
   // Test that array allocations are not considered usable after a
@@ -204,4 +207,49 @@
   EXPECT(store_into_array->ShouldEmitStoreBarrier() == true);
 }
 
+ISOLATE_UNIT_TEST_CASE(IRTest_WriteBarrierElimination_Regress43786) {
+  DEBUG_ONLY(
+      SetFlagScope<bool> sfs(&FLAG_trace_write_barrier_elimination, true));
+  const char* kScript = R"(
+      foo() {
+        final root = List<dynamic>.filled(128, null);
+        List<dynamic> last = root;
+        for (int i = 0; i < 10 * 1024; ++i) {
+          final nc = List(128);
+          last[0] = nc;
+          last = nc;
+        }
+      }
+
+      main() { foo(); }
+      )";
+
+  const auto& root_library = Library::Handle(LoadTestScript(kScript));
+
+  Invoke(root_library, "main");
+
+  const auto& function = Function::Handle(GetFunction(root_library, "foo"));
+  TestPipeline pipeline(function, CompilerPass::kJIT);
+  FlowGraph* flow_graph = pipeline.RunPasses({});
+
+  auto entry = flow_graph->graph_entry()->normal_entry();
+  EXPECT(entry != nullptr);
+
+  StoreIndexedInstr* store_into_phi = nullptr;
+
+  ILMatcher cursor(flow_graph, entry);
+  RELEASE_ASSERT(cursor.TryMatch(
+      {
+          kMatchAndMoveCreateArray,
+          kMatchAndMoveGoto,
+          kMatchAndMoveBranchTrue,
+          kMatchAndMoveCreateArray,
+          {kMatchAndMoveStoreIndexed, &store_into_phi},
+      },
+      kMoveGlob));
+
+  EXPECT(store_into_phi->array()->definition()->IsPhi());
+  EXPECT(store_into_phi->ShouldEmitStoreBarrier());
+}
+
 }  // namespace dart
diff --git a/tools/VERSION b/tools/VERSION
index a469e53..d065d49 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -28,4 +28,4 @@
 MINOR 11
 PATCH 0
 PRERELEASE 213
-PRERELEASE_PATCH 1
\ No newline at end of file
+PRERELEASE_PATCH 4
\ No newline at end of file