Merge kernel closure conversion into the Dart SDK

pkg/kernel/test/closures_test.dart

+// Copyright (c) 2016, 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.md file.
+
+library test.kernel.closures_test;
+
+import 'package:test/test.dart' show
+    Timeout,
+    test;
+
+import 'package:testing/testing.dart' show
+    run;
+
+main() {
+  test("closures", () => run([], ["closures"],
+                             "pkg/kernel/test/closures/testing.json"),
+      timeout: new Timeout(new Duration(minutes: 5)));
+}