Added back helper file accidentally deleted during test block 219 migration.

tests/lib/mirrors/dart2js_mirrors_test.dart

Index: tests/lib/mirrors/dart2js_mirrors_test.dart
diff --git a/tests/lib/mirrors/dart2js_mirrors_test.dart b/tests/lib/mirrors/dart2js_mirrors_test.dart
deleted file mode 100644
index 65c32e3ffa43257816f4d4b8ead2d4b277d3c95b..0000000000000000000000000000000000000000
--- a/tests/lib/mirrors/dart2js_mirrors_test.dart
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright (c) 2013, 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 test should be removed when dart2js can pass all mirror tests.
-// TODO(ahe): Remove this test.
-
-import 'mirrors_test.dart' as test;
-
-main() {
-  test.isDart2js = true;
-  test.main();
-}