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

tests/compiler/dart2js_native/native_class_inheritance1_frog_test.dart

 // Copyright (c) 2011, 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 "dart:_js_helper";
 import "package:expect/expect.dart";
 
 // Test to see if resolving a hidden native class's method interferes with
 // subsequent resolving the subclass's method.  This might happen if the
 // superclass caches the method in the prototype, so shadowing the dispatcher
 // stored on Object.prototype.
 
 // Version 1: It might be possible to call foo directly.
-class A1 native "A1" {
+@Native("A1")
+class A1 {
   foo() native;
 }
 
-class B1 extends A1 native "B1" {
+@Native("B1")
+class B1 extends A1 {
   foo() native;
 }
 
 makeA1() native;
 makeB1() native;
 
 
 // Version 2: foo needs some kind of trampoline.
-class A2 native "A2" {
+@Native("A2")
+class A2 {
   foo([a=99]) native;
 }
 
-class B2 extends A2 native "B2" {
+@Native("B2")
+class B2 extends A2 {
   foo([z=1000]) native;
 }
 
 makeA2() native;
 makeB2() native;
 
 void setup() native """
 // This code is all inside 'setup' and so not accesible from the global scope.
 function inherits(child, parent) {
   if (child.prototype.__proto__) {
@@ skipping 53 matching lines @@
   caught = false;
   try {
     var x = 123;
     x.foo(20);
   } catch (ex) {
     caught = true;
     Expect.isTrue(ex is NoSuchMethodError);
   }
   Expect.isTrue(caught, "x.foo(20) should throw");
 }