Add @MirrorsUsed annotations to speed up tests.

tests/lib/mirrors/lazy_static_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.
 
 // Test static members.
 
+library lib;
+
+@MirrorsUsed(targets: "lib")
 import 'dart:mirrors';
 
 import 'package:expect/expect.dart';
 
 import 'stringify.dart';
 
 class Foo {
   static var hello = {
     'a': 'b',
     'c': 'd',
   };
 }
 
 void main() {
   expect('Variable(s(hello) in s(Foo), static)',
          reflectClass(Foo).declarations[#hello]);
   var reflectee = reflectClass(Foo).getField(#hello).reflectee;
   Expect.stringEquals('a, c', reflectee.keys.join(', '));
   // Call the lazy getter twice as different things probably happen in the
   // underlying implementation.
   reflectee = reflectClass(Foo).getField(#hello).reflectee;
   Expect.stringEquals('a, c', reflectee.keys.join(', '));
   var value = 'fisk';
   Foo.hello = value;
   reflectee = reflectClass(Foo).getField(#hello).reflectee;
   Expect.identical(value, reflectee);
 }