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

tests/compiler/dart2js_native/native_field_invocation4_test.dart

Index: tests/compiler/dart2js_native/native_field_invocation4_test.dart
diff --git a/tests/compiler/dart2js_native/native_field_invocation4_test.dart b/tests/compiler/dart2js_native/native_field_invocation4_test.dart
index 28409264d20b574f74a0c2838188a67957667e68..e0a5c002f545545fb55225db4e3e2618d1802ec5 100644
--- a/tests/compiler/dart2js_native/native_field_invocation4_test.dart
+++ b/tests/compiler/dart2js_native/native_field_invocation4_test.dart
@@ -2,9 +2,11 @@
 // 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";
 
-class A native "A" {
+@Native("A")
+class A {
   var foo;
 }