anchor.diff:    void set rotation(double rotation) {
       assert(rotation != null);
       _rotation = rotation;
  -    _invalidateTransformMatrix();
  +    invalidateTransformMatrix();
     }
   
     /// The position of this node relative to its parent.
  
positive.code:   void set position(Point position) {
      assert(position != null);
      _position = position;
      _invalidateTransformMatrix();
    }
  
    /// The draw order of this node compared to its parent and its siblings.
  
negative.code:   void set scaleX(double scaleX) {
      assert(scaleX != null);
      _scaleX = scaleX;
      invalidateTransformMatrix();
    }
  
    /// The vertical scale of this node relative its parent.
  