Breaking Change: Support @JS at library level

tests/html/mirrors_js_typed_interop_test.dart

 // Copyright (c) 2015, 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.
 
+@JS()
 library tests.html.mirrors_js_typed_interop_test;
 
 import 'dart:mirrors';
 import 'dart:html';
 
 import 'package:js/js.dart';
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_config.dart';
 
 _injectJs() {
@@ skipping 24 matching lines @@
   useHtmlConfiguration();
 
   test('dynamic dispatch', () {
     var f = foo;
     expect(f.x, 3);
     // JsInterop methods are not accessible using reflection.
     expect(() => reflect(f).setField(#x, 123), throws);
     expect(f.x, 3);
   });
 }