Port DocumentFragment to the new wrapperless DOM.

client/dom/templates/html/dartium/html_dartium.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.
 
 // DO NOT EDIT
 // Auto-generated dart:html library.
 
 #library("html");
 
 #import('dart:dom', prefix:'dom');
@@ skipping 60 matching lines @@
 _wrap(raw) {
   if (raw is! dom.DOMType) return raw;
   dom.DOMType domObject = raw;
   if (domObject.dartObjectLocalStorage != null)
     return domObject.dartObjectLocalStorage;
   switch(domObject.typeName) {
     case 'HTMLDocument':
       throw 'A document should never be wrapped directly. TODO(jacobr) XXX';
     case 'HTMLHtmlElement':
       return new _DocumentImpl._wrap(domObject);
+    case 'HTMLElement':
+      return new _UnknownElementImpl._wrap(domObject);
 $WRAPCASES
     default:
       throw 'Unrecognized object $domObject. Name=${domObject.typeName}';
   }
 }