anchor.diff:  
   class TextFragment extends RenderNodeWrapper {
   
  -  RenderCSSInline _root;
  -  RenderCSSInline _createNode() => new RenderCSSInline(this, this.data);
  +  RenderCSSInline root;
  +  RenderCSSInline createNode() => new RenderCSSInline(this, this.data);
   
     static final TextFragment _emptyText = new TextFragment('');
   
  -  RenderNodeWrapper get _emptyNode => _emptyText;
  +  RenderNodeWrapper get emptyNode => _emptyText;
   
     final String data;
   
  
positive.code:     currentNode = null;
      while (oldStartIndex < oldEndIndex) {
        oldNode = oldChildren[oldStartIndex];
        _removeChild(oldNode);
        advanceOldStartIndex();
      }
    }
  
negative.code: 
  class FlexContainer extends OneChildListRenderNodeWrapper {
  
    RenderCSSFlex root;
    RenderCSSFlex createNode() => new RenderCSSFlex(this, this.direction);
  
    static final FlexContainer _emptyContainer = new FlexContainer();
      // direction doesn't matter if it's empty
  
    RenderNodeWrapper get emptyNode => _emptyContainer;
  
    final FlexDirection direction;
  
  