Add @MirrorsUsed annotations to speed up tests.

tests/lib/mirrors/intercepted_superclass_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.
 
 library test.intercepted_superclass_test;
 
+@MirrorsUsed(targets: const [#String, #int, #double, #num, #bool, #List])
 import 'dart:mirrors';
 import 'package:expect/expect.dart';
 
 check(ClassMirror cm){
   Expect.isTrue(cm is ClassMirror);
   Expect.isNotNull(cm);
 }
 
 main() {
   check(reflect('').type.superclass);
   check(reflect(1).type.superclass);
   check(reflect(1.5).type.superclass);
   check(reflect(true).type.superclass);
   check(reflect(false).type.superclass);
   check(reflect([]).type.superclass);
 
   check(reflectClass(String).superclass);
   check(reflectClass(int).superclass);
   check(reflectClass(double).superclass);
   check(reflectClass(num).superclass);
   check(reflectClass(bool).superclass);
   check(reflectClass(List).superclass);
 }