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

tests/compiler/dart2js_native/subclassing_4_test.dart

Index: tests/compiler/dart2js_native/subclassing_4_test.dart
diff --git a/tests/compiler/dart2js_native/subclassing_4_test.dart b/tests/compiler/dart2js_native/subclassing_4_test.dart
index 9d25e1a448e09543c0c6cf6847a6144ae949c89e..4997bb2b06498e0c91df65d29e96c5c387e02cef 100644
--- a/tests/compiler/dart2js_native/subclassing_4_test.dart
+++ b/tests/compiler/dart2js_native/subclassing_4_test.dart
@@ -3,7 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
-import 'dart:_js_helper' show Creates, setNativeSubclassDispatchRecord;
+import 'dart:_js_helper' show Native, Creates, setNativeSubclassDispatchRecord;
 import 'dart:_interceptors' show Interceptor, findInterceptorForType;
 
 // Test calling convention on subclasses of native classes.
@@ -12,7 +12,8 @@ class M {
   miz() => 'M';
 }
 
-class N native "N" {}
+@Native("N")
+class N {}
 
 class A extends N {}