Use @Native annotation on dart2js DOM native classes

tools/dom/templates/html/impl/impl_AudioNode.darttemplate

 // Copyright (c) 2012, 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.
 
 part of web_audio;
 
-$(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
+$(ANNOTATIONS)$(NATIVESPEC)class $CLASSNAME$EXTENDS$IMPLEMENTS {
 $!MEMBERS
   @DomName('AudioNode.connect')
   void connectNode(AudioNode destination, [int output = 0, int input = 0]) =>
       _connect(destination, output, input);
 
   @DomName('AudioNode.connect')
   void connectParam(AudioParam destination, [int output = 0]) =>
       _connect(destination, output);
 }