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

tools/dom/templates/html/impl/impl_Document.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.
 
 part of $LIBRARYNAME;
 
 @DocsEditable()
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME extends Node
 {
 
 $!MEMBERS
   /**
    * Finds all descendant elements of this document that match the specified
    * group of selectors.
    *
    * Unless your webpage contains multiple documents, the top-level
    * [querySelectorAll]
    * method behaves the same as this method, so you should use it instead to
    * save typing a few characters.
    *
    * [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) {
-    return new _FrozenElementList._wrap(_querySelectorAll(selectors));
-  }
+  ElementList<Element /*=T*/> querySelectorAll/*<T extends Element>*/(String selectors) =>
+    new _FrozenElementList/*<T>*/._wrap(_querySelectorAll(selectors));
 
   /**
    * Alias for [querySelector]. Note this function is deprecated because its
    * semantics will be changing in the future.
    */
   @deprecated
   @Experimental()
   @DomName('Document.querySelector')
   Element query(String relativeSelectors) => querySelector(relativeSelectors);
 
   /**
    * Alias for [querySelectorAll]. Note this function is deprecated because its
    * semantics will be changing in the future.
    */
   @deprecated
   @Experimental()
   @DomName('Document.querySelectorAll')
-  ElementList<Element> queryAll(String relativeSelectors) =>
+  ElementList<Element /*=T*/> queryAll/*<T extends Element>*/(String relativeSelectors) =>
       querySelectorAll(relativeSelectors);
 
   /// Checks if [registerElement] is supported on the current platform.
   bool get supportsRegisterElement {
 $if DART2JS
     return JS('bool', '("registerElement" in #)', this);
 $else
     return true;
 $endif
   }
@@ skipping 63 matching lines @@
   @SupportedBrowser(SupportedBrowser.IE, '10')
   @Experimental()
 $if DART2JS
   String get visibilityState => JS('String',
     '(#.visibilityState || #.mozVisibilityState || #.msVisibilityState ||'
       '#.webkitVisibilityState)', this, this, this, this);
 $else
   String get visibilityState => _visibilityState;
 $endif
 }