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

tests/compiler/dart2js_native/subclassing_constructor_1_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 that subclasses of native classes can be initialized by calling the
 // 'upgrade' constructor.
 
 var trace = [];
 
 var log;
 
-class A native "A" {
+@Native("A")
+class A {
   final a1 = log(101);  // Only initialized IF named constructor called.
   final a2;             // Initialized by native constructor.
   final a3;             // Initialized only by A.two.
   var a4 = log(104);
 
   A.one();
 
   A.two() : a3 = log(103) {
     log('body(A.two)');
     log(a4 += increment);
@@ skipping 138 matching lines @@
     return message;
   };
 
   setNativeSubclassDispatchRecord(getBPrototype(), findInterceptorForType(B));
 
   test_one();
   test_two();
   test_three();
   test_new();
 }