Use @Native annotation on dart2js DOM native classes

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

 // 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.
 
 part of $LIBRARYNAME;
 
 @DocsEditable()
-$(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$MIXINS$IMPLEMENTS$NATIVESPEC {
+$(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$MIXINS$IMPLEMENTS {
 $!MEMBERS
 
   DataTransferItem operator[] (int index) {
 $if DART2JS
     return JS('DataTransferItem', '#[#]', this, index);
 $else
     return __getter__(index);
 $endif
   }
 
 }