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

tests/compiler/dart2js_native/bound_closure_test.dart

 // Copyright (c) 2013, 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 calling convention of property extraction closures.
 
 class AA {
   bar(a, [b = 'A']) => 'AA.bar($a, $b)';   // bar is plain dart convention.
   foo(a, [b = 'A']) => 'AA.foo($a, $b)';   // foo has interceptor convention.
 }
 
-class BB native "BB" {
+@Native("BB")
+class BB {
   foo(a, [b = 'B']) native;
 }
 
-class CC extends BB native "CC" {
+@Native("CC")
+class CC extends BB {
   foo(a, [b = 'C']) native;
 
   get superfoo => super.foo;
 }
 
 makeBB() native;
 makeCC() native;
 inscrutable(a) native;
 
 void setup() native r"""
@@ skipping 41 matching lines @@
 
   Expect.equals('AA.foo(1, A)', afoo(1));
   Expect.equals('AA.foo(2, 3)', afoo(2, 3));
 
   Expect.equals('BB.foo(1, B)', bfoo(1));
   Expect.equals('BB.foo(2, 3)', bfoo(2, 3));
 
   Expect.equals('CC.foo(1, C)', cfoo(1));
   Expect.equals('CC.foo(2, 3)', cfoo(2, 3));
 }