Add @Native(...) annotation for native class names.

tests/compiler/dart2js_native/jsobject_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.
 
 import "package:expect/expect.dart";
-import 'dart:_js_helper' show Creates, setNativeSubclassDispatchRecord;
+import 'dart:_js_helper' show Native, Creates, setNativeSubclassDispatchRecord;
 import 'dart:_interceptors' show
     JSObject,                 // The interface, which may be re-exported by a
                               // js-interop library.
     JavaScriptObject,         //   The interceptor abstract class.
     PlainJavaScriptObject,    //     The interceptor concrete class.
     UnknownJavaScriptObject,  //     The interceptor concrete class.
     Interceptor;
 
 // Test for JavaScript objects from outside the Dart program.  Although we only
 // export the interface [JSObject] to user level code, this test makes sure we
@@ skipping 72 matching lines @@
   Expect.isTrue(isQ(x));
   Expect.isFalse(x.runtimeType == JSObject);
 }
 
 main() {
   setup();
 
   dynamic_test();
   static_test();
 }