Use @Native annotation on dart2js DOM native classes

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

 // Copyright (c) 2011, 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;
 
-$(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
+$(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
   factory $CLASSNAME() => document.createDocumentFragment();
 
   factory $CLASSNAME.html(String html,
       {NodeValidator validator, NodeTreeSanitizer treeSanitizer}) {
 
     return document.body.createFragment(html,
       validator: validator, treeSanitizer: treeSanitizer);
   }
 
   factory $CLASSNAME.svg(String svgContent,
@@ skipping 95 matching lines @@
    * semantics will be changing in the future.
    */
   @deprecated
   @Experimental()
   @DomName('DocumentFragment.querySelectorAll')
   ElementList queryAll(String relativeSelectors) {
     return querySelectorAll(relativeSelectors);
   }
 $!MEMBERS
 }