anchor.diff:    void set scaleY(double scaleY) {
       assert(scaleY != null);
       _scaleY = scaleY;
  -    _invalidateTransformMatrix();
  +    invalidateTransformMatrix();
     }
   
     /// A list of the children of this node.
  
positive.code:     }
  
      // Create transformation matrix for scale, position and rotation
      _transformMatrix = new Matrix4(cy * _scaleX, sy * _scaleX, 0.0, 0.0,
                 -sx * _scaleY, cx * _scaleY, 0.0, 0.0,
                 0.0, 0.0, 1.0, 0.0,
                _position.x, _position.y, 0.0, 1.0);
  
      return _transformMatrix;
    }
  
    void _invalidateTransformMatrix() {
      _transformMatrix = null;
      _invalidateToBoxTransformMatrix();
    }
  
negative.code:   void set scaleX(double scaleX) {
      assert(scaleX != null);
      _scaleX = scaleX;
      invalidateTransformMatrix();
    }
  
    /// The vertical scale of this node relative its parent.
  