anchor.diff:      }
     }
   
  -  void _syncNode(RenderNode old) {
  -    WrapperNode oldWrapperNode = old as WrapperNode;
  +  void _syncNode(SkyNodeWrapper old) {
  +    SkyElementWrapper oldSkyElementWrapper = old as SkyElementWrapper;
       sky.Element root = _root as sky.Element;
   
       _ensureClass();
  -    if (_class != oldWrapperNode._class && _class != '')
  +    if (_class != oldSkyElementWrapper._class && _class != '')
         root.setAttribute('class', _class);
   
  -    if (inlineStyle != oldWrapperNode.inlineStyle)
  +    if (inlineStyle != oldSkyElementWrapper.inlineStyle)
         root.setAttribute('style', inlineStyle);
   
  -    _syncChildren(oldWrapperNode);
  -  }
  -
  -  void _syncChildren(WrapperNode oldWrapperNode) {
  +    _syncChildren(oldSkyElementWrapper);
  +  }
  +
  +  void _syncChildren(SkyElementWrapper oldSkyElementWrapper) {
       sky.Element root = _root as sky.Element;
       assert(root != null);
   
       var startIndex = 0;
       var endIndex = children.length;
   
  -    var oldChildren = oldWrapperNode.children;
  +    var oldChildren = oldSkyElementWrapper.children;
       var oldStartIndex = 0;
       var oldEndIndex = oldChildren.length;
   
  
positive.code: 
  final List<UINode> _emptyList = new List<UINode>();
  
  abstract class WrapperNode extends RenderNode {
  
    String get _tagName;
  
  
negative.code: 
    static final Text _emptyText = new Text(null);
  
    SkyNodeWrapper get _emptyNode => _emptyText;
  
    sky.Node _createNode() {
      return new sky.Text(data);
    }
  
    void _syncNode(SkyNodeWrapper old) {
      if (old == _emptyText)
        return; // we set inside _createNode();
  
  