Cleanup queryAll to return List<Element>.

lib/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.
 
 class FilteredElementList implements ElementList {
   final Node _node;
   final NodeList _childNodes;
 
   FilteredElementList(Node node): _childNodes = node.nodes, _node = node;
 
@@ skipping 129 matching lines @@
   void set elements(value) {
     // Copy list first since we don't want liveness during iteration.
     List copy = new List.from(value);
     final elements = this.elements;
     elements.clear();
     elements.addAll(copy);
   }
 
   _ElementImpl query(String selectors) => $dom_querySelector(selectors);
 
-  ElementList queryAll(String selectors) =>
+  List<Element> queryAll(String selectors) =>
     new _FrozenElementList._wrap($dom_querySelectorAll(selectors));
 
   String get innerHTML() {
     final e = new Element.tag("div");
     e.nodes.add(this.clone(true));
     return e.innerHTML;
   }
 
   String get outerHTML() => innerHTML;
 
@@ skipping 176 matching lines @@
       "WebKit drop zone can't be set for document fragments.");
   }
 
   void set webkitRegionOverflow(String value) {
     throw new UnsupportedOperationException(
       "WebKit region overflow can't be set for document fragments.");
   }
 
 $!MEMBERS
 }