Extension method support to move us closer to a valid List implementation.

test/dart_codegen/expect/core/annotations.dart

Index: test/dart_codegen/expect/core/annotations.dart
diff --git a/test/dart_codegen/expect/core/annotations.dart b/test/dart_codegen/expect/core/annotations.dart
index 1be08c7d69987317a037c841962f401dd163d248..991a63fbba23217242d098bdc75bfb4a1294543c 100644
--- a/test/dart_codegen/expect/core/annotations.dart
+++ b/test/dart_codegen/expect/core/annotations.dart
@@ -1,4 +1,16 @@
 part of dart.core;
+ class JsName {final String name;
+ const JsName({
+  this.name}
+);
+}
+ class JsPeerInterface {final String name;
+ const JsPeerInterface({
+this.name}
+);
+}
+ class SupportJsExtensionMethod {const SupportJsExtensionMethod();
+}
  class Deprecated {final String expires;
  const Deprecated(String expires) : this.expires = expires;
  String toString() => "Deprecated feature. Will be removed $expires";