anchor.diff:      this.height: 400,
       List<Color> colors,
       this.onClick}) :
  -      colors = colors == null ? defaultColors : _makeCssColors(colors)
  +      this.colors = (colors == null) ? defaultColors : colors
     {
       var radiusPixels = width < height ? width/2.0 : height/2.0;
       scalePixel = radius / radiusPixels;
  
positive.code:   final int width;
    final int height;
    final ClickHandler onClick;
    final List<String> colors;
    double scalePixel;
  
    MandelbrotView({
  
negative.code:   }
  
    @override
    int get hashCode => center.hashCode ^ radius.hashCode ^ width ^ height;
  
    @override
    start() => new Place<MandelbrotView>(this);
  
    @override
  