Revert "Flutter 1.24 (#619)" (#621)

diff --git a/Dockerfile b/Dockerfile
index 4ee5e79..115bcff 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -6,7 +6,7 @@
 # To retrieve this value, please run the following in your closest shell:
 #
 # $ (cd flutter && git rev-parse HEAD)
-ARG FLUTTER_COMMIT=022b333a089afb81c471ec43d1f1f4f26305d876
+ARG FLUTTER_COMMIT=198df796aa80073ef22bdf249e614e2ff33c6895
 
 # We install unzip and remove the apt-index again to keep the
 # docker image diff small.
diff --git a/cloud_run.Dockerfile b/cloud_run.Dockerfile
index 168cd62..17877fa 100644
--- a/cloud_run.Dockerfile
+++ b/cloud_run.Dockerfile
@@ -6,7 +6,7 @@
 # To retrieve this value, please run the following in your closest shell:
 #
 # $ (cd flutter && git rev-parse HEAD)
-ARG FLUTTER_COMMIT=022b333a089afb81c471ec43d1f1f4f26305d876
+ARG FLUTTER_COMMIT=198df796aa80073ef22bdf249e614e2ff33c6895
 
 # We install unzip and remove the apt-index again to keep the
 # docker image diff small.
diff --git a/example/pubspec.lock b/example/pubspec.lock
index 957383a..1a2ffbc 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -175,7 +175,14 @@
       name: dart_style
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.9"
+    version: "1.3.10"
+  file:
+    dependency: transitive
+    description:
+      name: file
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "5.2.1"
   fixnum:
     dependency: transitive
     description:
@@ -218,6 +225,13 @@
       url: "https://pub.dartlang.org"
     source: hosted
     version: "3.1.4"
+  intl:
+    dependency: transitive
+    description:
+      name: intl
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.16.1"
   io:
     dependency: transitive
     description:
@@ -238,7 +252,7 @@
       name: json_annotation
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "3.1.0"
+    version: "3.1.1"
   logging:
     dependency: transitive
     description:
@@ -273,14 +287,14 @@
       name: node_interop
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0"
+    version: "1.2.1"
   node_io:
     dependency: transitive
     description:
       name: node_io
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.1"
+    version: "1.2.0"
   package_config:
     dependency: transitive
     description:
diff --git a/flutter b/flutter
index 022b333..198df79 160000
--- a/flutter
+++ b/flutter
@@ -1 +1 @@
-Subproject commit 022b333a089afb81c471ec43d1f1f4f26305d876
+Subproject commit 198df796aa80073ef22bdf249e614e2ff33c6895
diff --git a/lib/src/common.dart b/lib/src/common.dart
index a5fd1a1..27e0be8 100644
--- a/lib/src/common.dart
+++ b/lib/src/common.dart
@@ -38,7 +38,7 @@
 
 void main() {
   print("hello");
-  querySelector('#foo')?.text = 'bar';
+  querySelector('#foo').text = 'bar';
 }
 """;
 
@@ -83,7 +83,7 @@
 
 main() async {
   print("hello");
-  querySelector('#foo')?.text = 'bar';
+  querySelector('#foo').text = 'bar';
   var foo = await HttpRequest.getString('http://www.google.com');
   print(foo);
 }
diff --git a/lib/src/flutter_web.dart b/lib/src/flutter_web.dart
index 10dabd0..8458400 100644
--- a/lib/src/flutter_web.dart
+++ b/lib/src/flutter_web.dart
@@ -171,11 +171,8 @@
   static const String _samplePackageName = 'dartpad_sample';
 
   static String createPubspec(bool includeFlutterWeb) {
-    // Mark the samples as not null safe.
     var content = '''
 name: $_samplePackageName
-environment:
-  sdk: '>=2.10.0 <3.0.0'
 ''';
 
     if (includeFlutterWeb) {
diff --git a/pubspec.lock b/pubspec.lock
index c6b5b39..52f97c3 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -204,6 +204,13 @@
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.5.0"
+  file:
+    dependency: transitive
+    description:
+      name: file
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "5.2.1"
   fixnum:
     dependency: transitive
     description:
@@ -336,7 +343,7 @@
       name: json_annotation
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "3.1.0"
+    version: "3.1.1"
   logging:
     dependency: "direct main"
     description:
@@ -378,14 +385,14 @@
       name: node_interop
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0"
+    version: "1.2.1"
   node_io:
     dependency: transitive
     description:
       name: node_io
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.1"
+    version: "1.2.0"
   node_preamble:
     dependency: transitive
     description:
@@ -567,7 +574,7 @@
       name: test
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.15.5"
+    version: "1.15.6"
   test_api:
     dependency: transitive
     description:
@@ -581,7 +588,7 @@
       name: test_core
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.3.11+2"
+    version: "0.3.11+3"
   timing:
     dependency: transitive
     description: