Add @MirrorsUsed annotations to speed up tests.

tests/lib/mirrors/generic_interface_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.generic_bounded;
 
+@MirrorsUsed(targets: "test.generic_bounded")
 import 'dart:mirrors';
 
 import 'package:expect/expect.dart';
 
 import 'generics_helper.dart';
 
 class Interface<T> {}
 class Bounded<S extends num> {}
 
 class Fixed implements Interface<int> {}
@@ skipping 84 matching lines @@
   typeArguments(boundedOfInt, [reflectClass(int)]);
   typeArguments(boundedOfString, [reflectClass(String)]);  /// 01: continued
   typeArguments(interfaceOfFBounded, [reflectClass(FBounded)]);
   typeArguments(interfaceOfInt2, [reflectClass(int)]);
   typeArguments(interfaceOfX, [xFromGenericMixinApplication]);
   typeArguments(interfaceOfDouble, [reflectClass(double)]);
   typeArguments(interfaceOfInt3, [reflectClass(int)]);
   typeArguments(interfaceOfY, [yFromGenericClass]);
   typeArguments(interfaceOfDouble2, [reflectClass(double)]);
 }