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

tools/dom/templates/html/impl/impl_Document.darttemplate

Index: tools/dom/templates/html/impl/impl_Document.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Document.darttemplate b/tools/dom/templates/html/impl/impl_Document.darttemplate
index c87a9216c11269ae2455988d992688fba70e22c2..7c8a1241fc497b660ce6cc075a7712dd7d8f8150 100644
--- a/tools/dom/templates/html/impl/impl_Document.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Document.darttemplate
@@ -25,9 +25,8 @@ $!MEMBERS
    * 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
@@ -45,7 +44,7 @@ $!MEMBERS
   @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.