[dart2js] Migrate shared libraries to 2.12

Change-Id: I5600fe01e90963b56a6ffa36ec9edf0096088b2b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/202000
Reviewed-by: Mayank Patke <fishythefish@google.com>
Commit-Queue: Stephen Adams <sra@google.com>

pkg/js_runtime/lib/shared/async_await_error_codes.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.
 
+// @dart=2.12
+
 /// Contains error codes that transformed async/async* functions use to
 /// communicate with js_helper functions.
 

pkg/js_runtime/lib/shared/embedded_names.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.
 
+// @dart=2.12
+
 /// Contains the names of globals that are embedded into the output by the
 /// compiler.
 ///

pkg/js_runtime/lib/shared/recipe_syntax.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.
 
+// @dart=2.12
+
 /// Constants and predicates used for encoding and decoding type recipes.
 ///
 /// This library is shared between the compiler and the runtime system.

sdk/lib/_internal/js_runtime/lib/shared/async_await_error_codes.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.
 
+// @dart=2.12
+
 /// Contains error codes that transformed async/async* functions use to
 /// communicate with js_helper functions.
 

sdk/lib/_internal/js_runtime/lib/shared/embedded_names.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.
 
+// @dart=2.12
+
 /// Contains the names of globals that are embedded into the output by the
 /// compiler.
 ///

sdk/lib/_internal/js_runtime/lib/shared/recipe_syntax.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.
 
+// @dart=2.12
+
 /// Constants and predicates used for encoding and decoding type recipes.
 ///
 /// This library is shared between the compiler and the runtime system.