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

tests/compiler/dart2js_native/native_field_name_test.dart

Index: tests/compiler/dart2js_native/native_field_name_test.dart
diff --git a/tests/compiler/dart2js_native/native_field_name_test.dart b/tests/compiler/dart2js_native/native_field_name_test.dart
index 8eab52b81b1172c3411718c612aa6c4f3ae48925..42af8880ae1dfc279d1c5d8ba5f6ddf24a748894 100644
--- a/tests/compiler/dart2js_native/native_field_name_test.dart
+++ b/tests/compiler/dart2js_native/native_field_name_test.dart
@@ -2,11 +2,13 @@
 // 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";
 
 // Check that native fields are not incorrectly renamed.
 
-class A native "A" {
+@Native("A")
+class A {
   int myLongPropertyName;
   int getValue;