Make querySelectorAll a generic method so that checked mode behavior is consistent with existing be…

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;
 
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
   factory $CLASSNAME() => document.createDocumentFragment();
 
   factory $CLASSNAME.html(String html,
@@ skipping 39 matching lines @@
    * Finds all descendant elements of this document fragment that match the
    * specified group of selectors.
    *
    * [selectors] should be a string using CSS selector syntax.
    *
    *     var items = document.querySelectorAll('.itemClassName');
    *
    * For details about CSS selector syntax, see the
    * [CSS selector specification](http://www.w3.org/TR/css3-selectors/).
    */
-  ElementList<Element> querySelectorAll(String selectors) =>
-    new _FrozenElementList._wrap(_querySelectorAll(selectors));
+  ElementList<Element /*=T*/> querySelectorAll/*<T extends Element>*/(String selectors) =>
+    new _FrozenElementList/*<T>*/._wrap(_querySelectorAll(selectors));
+
 
   String get innerHtml {
     final e = new Element.tag("div");
     e.append(this.clone(true));
     return e.innerHtml;
   }
 
   set innerHtml(String value) {
     this.setInnerHtml(value);
   }
@@ skipping 36 matching lines @@
     return querySelector(relativeSelectors);
   }
 
   /** 
    * Alias for [querySelectorAll]. Note this function is deprecated because its
    * semantics will be changing in the future.
    */
   @deprecated
   @Experimental()
   @DomName('DocumentFragment.querySelectorAll')
-  ElementList<Element> queryAll(String relativeSelectors) {
-    return querySelectorAll(relativeSelectors);
-  }
+  ElementList<Element /*=T*/> queryAll/*<T extends Element>*/(String relativeSelectors) =>
+    querySelectorAll(relativeSelectors);
 $!MEMBERS
 }