Add @MirrorsUsed annotations to speed up tests.

tests/lib/mirrors/generic_bounded_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 Super<T extends num> {}
 
 class Fixed extends Super<int> {}
 class Generic<R> extends Super<R> {}  /// 02: static type warning
@@ skipping 57 matching lines @@
   typeParameters(superOfString, [#T]);  /// 01: continued
 
   typeArguments(superDecl, []);
   typeArguments(superOfInt, [reflectClass(int)]);
   typeArguments(genericDecl, []);  /// 02: continued
   typeArguments(superOfR, [rFromGeneric]);  /// 02: continued
   typeArguments(genericOfDouble, [reflectClass(double)]);  /// 02: continued
   typeArguments(superOfDouble, [reflectClass(double)]);  /// 02: continued
   typeArguments(superOfString, [reflectClass(String)]);  /// 01: continued
 }