anchor.diff:  }
   
   class FlexExpandingChild extends ParentDataNode {
  -  FlexExpandingChild(UINode content, [int flex = 1]): super(content, new FlexBoxParentData()..flex = flex);
  -}
  -
  -class FillStackContainer extends OneChildListRenderNodeWrapper {
  -
  -  RenderCSSStack root;
  -  RenderCSSStack createNode() => new RenderCSSStack(this);
  -
  -  static final FillStackContainer _emptyContainer = new FillStackContainer();
  -
  -  RenderNodeWrapper get emptyNode => _emptyContainer;
  -
  -  FillStackContainer({
  -    Object key,
  -    List<UINode> children
  -  }) : super(
  -    key: key,
  -    children: _positionNodesToFill(children)
  -  );
  -
  -  static StackParentData _fillParentData = new StackParentData()
  -                                                 ..top = 0.0
  -                                                 ..left = 0.0
  -                                                 ..right = 0.0
  -                                                 ..bottom = 0.0;
  -
  -  static List<UINode> _positionNodesToFill(List<UINode> input) {
  -    if (input == null)
  -      return null;
  -    return input.map((node) {
  -      return new ParentDataNode(node, _fillParentData);
  -    }).toList();
  -  }
  -}
  -
  -abstract class OneChildRenderNodeWrapper extends RenderNodeWrapper {
  -
  -  final UINode child;
  -  RenderNodeWithChildMixin root;
  -
  -  OneChildRenderNodeWrapper({
  -    Object key,
  -    this.child
  -  }) : super(key: key);
  -
  -  void insert(RenderNodeWrapper child, dynamic slot) {
  -    assert(slot == null);
  -    root.child = child.root;
  -  }
  -
  -  void _remove() {
  -    assert(child != null);
  -    removeChild(child);
  -    super._remove();
  -  }
  +  FlexExpandingChild(UINode content, [int flex = 1])
  +    : super(content, new FlexBoxParentData()..flex = flex);
   }
   
   class Image extends RenderNodeWrapper {
  -
     RenderCSSImage root;
     RenderCSSImage createNode() => new RenderCSSImage(this, this.src, this.width, this.height);
  -
  -  static final Image _emptyImage = new Image();
  -
  -  RenderNodeWrapper get emptyNode => _emptyImage;
   
     final String src;
     final int width;
  
positive.code:   }) : super(key: key);
  
    RenderNode createNode();
    RenderNodeWrapper get emptyNode;
  
    void insert(RenderNodeWrapper child, dynamic slot);
  
  
negative.code:     this.width,
      this.height,
      this.src
    }) : super(key: key);
  
    void syncRenderNode(UINode old) {
      super.syncRenderNode(old);
  