Add @MirrorsUsed annotations to speed up tests.

tests/lib/mirrors/mixin_application_test.dart

 // 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 uses the multi-test "ok" feature to create two positive tests from
-// one file. One of these tests fail on dart2js, but pass on the VM, or vice
-// versa.
-// TODO(ahe): When both implementations agree, remove the multi-test parts.
-
 library test.mixin_application_test;
 
+@MirrorsUsed(targets: "test.mixin_application_test")
 import 'dart:mirrors';
 
 import 'package:expect/expect.dart';
 
 import 'model.dart';
 import 'stringify.dart';
 
 class Mixin {
   int i;
   m() {}
@@ skipping 314 matching lines @@
   testMixin();
   testMixin2();
   testMixinApplication();
   testMixinApplicationA();
   testUnusedMixinApplication();
   testSubclass();
   testSubclass2();
   testSubclassA();
   testSubclass2A();
 }