Make List.shuffle take an optional Random object to use.

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

Index: tools/dom/templates/html/impl/impl_Element.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Element.darttemplate b/tools/dom/templates/html/impl/impl_Element.darttemplate
index e87b381cde5c3900032aff326cc5b7ba9a979e91..7baf2b3d7a15272ea7ddbb5bebd9e1440864226e 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -58,7 +58,7 @@ class _ChildrenElementList extends ListBase<Element> {
     throw new UnsupportedError('Cannot sort element lists');
   }
 
-  void shuffle() {
+  void shuffle([Random random]) {
     throw new UnsupportedError('Cannot shuffle element lists');
   }
 
@@ -280,7 +280,7 @@ class _FrozenElementList<T extends Element> extends ListBase<T> implements Eleme
     throw new UnsupportedError('Cannot sort list');
   }
 
-  void shuffle() {
+  void shuffle([Random random]) {
     throw new UnsupportedError('Cannot shuffle list');
   }