Make RegExp constructor non-const.

sdk/lib/html/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 html;
 
 // TODO(jacobr): use _Lists.dart to remove some of the duplicated
 // functionality.
 class _ChildrenElementList implements List {
   // Raw Element.
@@ skipping 681 matching lines @@
   }
 $else
 $endif
 
 $!MEMBERS
 }
 
 // Temporary dispatch hook to support WebComponents.
 Function dynamicUnknownElementDispatcher;
 
-final _START_TAG_REGEXP = const RegExp('<(\\w+)');
+final _START_TAG_REGEXP = new RegExp('<(\\w+)');
 class _ElementFactoryProvider {
   static final _CUSTOM_PARENT_TAG_MAP = const {
     'body' : 'html',
     'head' : 'html',
     'caption' : 'table',
     'td': 'tr',
     'colgroup': 'table',
     'col' : 'colgroup',
     'tr' : 'tbody',
     'tbody' : 'table',
@@ skipping 42 matching lines @@
 $if DART2JS
   // Optimization to improve performance until the dart2js compiler inlines this
   // method.
   static Element createElement_tag(String tag) =>
       JS('Element', 'document.createElement(#)', tag);
 $else
   static Element createElement_tag(String tag) =>
       document.$dom_createElement(tag);
 $endif
 }