Revert two Kernel changes that were causing test failures.

tests/language_2/async_star_regression_2238_test.dart

Index: tests/language_2/async_star_regression_2238_test.dart
diff --git a/tests/language_2/async_star_regression_2238_test.dart b/tests/language_2/async_star_regression_2238_test.dart
deleted file mode 100644
index 9cfffa614a10136966d1aab4e7402e85b6ece40e..0000000000000000000000000000000000000000
--- a/tests/language_2/async_star_regression_2238_test.dart
+++ /dev/null
@@ -1,22 +0,0 @@
-// 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.
-
-// This is a regression test for issue 2238
-import "dart:async";
-import "package:expect/expect.dart";
-import "package:async_helper/async_helper.dart";
-
-main() {
-  f() async* {
-    label1:
-    label2:
-    yield 0;
-  }
-
-  asyncStart();
-  f().toList().then((list) {
-    Expect.listEquals([0], list);
-    asyncEnd();
-  });
-}