anchor.diff:  class Indicator {
     Point start;
     Point end;
  -  ParagraphPainter labelPainter;
  +  TextPainter labelPainter;
     Point labelPosition;
   }
   
   class ChartPainter {
  -  ChartPainter(ChartData data) : _data = data;
  +  ChartPainter(this._data);
   
     ChartData _data;
     ChartData get data => _data;
  
positive.code:   final ChartData data;
  
    RenderChart createNode() => new RenderChart(data: data);
    RenderChart get root => super.root;
  
    void syncRenderObject(Widget old) {
      super.syncRenderObject(old);
  
negative.code: 
  class Gridline {
    double value;
    TextPainter labelPainter;
    Point labelPosition;
    Point start;
    Point end;
  