anchor.diff:        }
   
         UINode parent = _parent;
  -      while (parent != null && parent is! RenderNode) {
  +      while (parent != null && parent is! SkyNodeWrapper) {
           if (parent is StyleNode && (parent as StyleNode).style != null)
             styles.add((parent as StyleNode).style);
   
  
positive.code: 
  final List<UINode> _emptyList = new List<UINode>();
  
  abstract class WrapperNode extends RenderNode {
  
    String get _tagName;
  
  
negative.code: }
  
  /*
   * SkyNodeWrappers correspond to a desired state of a sky.Node. They are fully
   * immutable, with one exception: A UINode which is a Component which lives within
   * an SkyElementWrapper's children list, may be replaced with the "old" instance if it
   * has become stateful.
   */
  abstract class SkyNodeWrapper extends UINode {
  
    static final Map<sky.Node, SkyNodeWrapper> _nodeMap =
        new HashMap<sky.Node, SkyNodeWrapper>();
  
    static SkyNodeWrapper _getMounted(sky.Node node) => _nodeMap[node];
  
    SkyNodeWrapper({ Object key }) : super(key: key);
  
    SkyNodeWrapper get _emptyNode;
  
    sky.Node _createNode();
  
  