anchor.diff:      _childrenHeight = y;
     }
   
  -  void hitTestChildren(HitTestResult result, { Point position }) {
  -    defaultHitTestChildren(result, position: position);
  -  }
  -
  -  void paint(PaintingCanvas canvas, Offset offset) {
  -    defaultPaint(canvas, offset);
  -  }
  -
   }
   
   class RenderBlock extends RenderBlockBase {
  
positive.code:   void setupParentData(RenderBox child) {
      if (child.parentData is! BlockParentData)
        child.parentData = new BlockParentData();
    }
  
    double computeDistanceToActualBaseline(TextBaseline baseline) {
      return defaultComputeDistanceToFirstActualBaseline(baseline);
    }
  
    double _childrenHeight;
  
negative.code:   double getMaxIntrinsicHeight(BoxConstraints constraints) {
      return constraints.constrainHeight();
    }
  
    // We don't override computeDistanceToActualBaseline(), because we
    // want the default behaviour (returning null). Otherwise, as you
    // scroll the RenderBlockViewport, it would shift in its parent if
    // the parent was baseline-aligned, which makes no sense.
  
    bool get sizedByParent => true;
  
  