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

tests/compiler/dart2js_native/subclassing_super_call_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:_foreign_helper' show JS;
-import 'dart:_js_helper' show Creates, setNativeSubclassDispatchRecord;
+import 'dart:_js_helper' show Native, Creates, setNativeSubclassDispatchRecord;
 import 'dart:_interceptors' show
     findInterceptorForType, findConstructorForNativeSubclassType;
 
 // Test for super access from classes that extend native classes.
 
-class N1 native "N1" {
+@Native("N1")
+class N1 {
 }
 
-class N2 extends N1 native "N2" {
+@Native("N2")
+class N2 extends N1 {
   N2.init();
   String text;
   foo() native;
 }
 
 class AA extends N2 {
   AA.init() : super.init();
   String afield;
   afun() => 'afun:$afield';
 }
@@ skipping 98 matching lines @@
 
 main() {
   setup();
   inscrutable = (x) => x;
 
   setNativeSubclassDispatchRecord(getBBPrototype(), findInterceptorForType(BB));
 
   testSuperOnNative();
   testSuperOnSubclassOfNative();
 }