Make DocumentFragment implement Element.

client/html/src/DocumentFragment.dart

Index: client/html/src/DocumentFragment.dart
diff --git a/client/html/src/DocumentFragment.dart b/client/html/src/DocumentFragment.dart
index 683af4ceddb59bde2b7566a0f99075eda9308c9d..c483c9cb5b06ce49ea9f239a4f2a4c8f57fdf85c 100644
--- a/client/html/src/DocumentFragment.dart
+++ b/client/html/src/DocumentFragment.dart
@@ -2,11 +2,9 @@
 // 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.
 
-interface DocumentFragment extends Node factory DocumentFragmentWrappingImplementation {
+interface DocumentFragment extends Element factory DocumentFragmentWrappingImplementation {
  
   DocumentFragment();
 
-  Element query(String selectors);
-
-  ElementList queryAll(String selectors);
+  DocumentFragment.html(String html);
 }