Fix bug in html library.

tools/dom/templates/html/impl/impl_Element.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;
 
 // TODO(jacobr): use _Lists.dart to remove some of the duplicated
 // functionality.
 class _ChildrenElementList implements List {
   // Raw Element.
   final Element _element;
   final HtmlCollection _childElements;
 
   _ChildrenElementList._wrap(Element element)
     : _childElements = element.$dom_children,
       _element = element;
 
   List<Element> toList({ bool growable: false }) {
-    final output;
+    List<Element> output;
     if (growable) {
       output = <Element>[];
       output.length = _childElements.length;
     } else {
       output = new List<Element>(_childElements.length);
     }
     for (int i = 0, len = _childElements.length; i < len; i++) {
       output[i] = _childElements[i];
     }
     return output;
@@ skipping 1085 matching lines @@
   const ScrollAlignment._internal(this._value);
   toString() => 'ScrollAlignment.$_value';
 
   /// Attempt to align the element to the top of the scrollable area.
   static const TOP = const ScrollAlignment._internal('TOP');
   /// Attempt to center the element in the scrollable area.
   static const CENTER = const ScrollAlignment._internal('CENTER');
   /// Attempt to align the element to the bottom of the scrollable area.
   static const BOTTOM = const ScrollAlignment._internal('BOTTOM');
 }