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

tests/compiler/dart2js_native/subclassing_constructor_2_test.dart

Index: tests/compiler/dart2js_native/subclassing_constructor_2_test.dart
diff --git a/tests/compiler/dart2js_native/subclassing_constructor_2_test.dart b/tests/compiler/dart2js_native/subclassing_constructor_2_test.dart
index 75e321c872298e066bb7daff630763e1ca4b1dd6..2b9f6c527d1cc6b9f58458ee0bbbbc5e17341b58 100644
--- a/tests/compiler/dart2js_native/subclassing_constructor_2_test.dart
+++ b/tests/compiler/dart2js_native/subclassing_constructor_2_test.dart
@@ -2,12 +2,14 @@
 // 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 that native classes and subclasses of native classes cannot be directly
 // created via a generative constructor.
 
-class A native "A" {
+@Native("A")
+class A {
   A.one();
 }