anchor.diff:    void paint(Canvas canvas, Size size) {
       Paint paint = new Paint()
         ..color = backgroundColor
  -      ..style = ui.PaintingStyle.fill;
  +      ..style = PaintingStyle.fill;
       canvas.drawRect(Point.origin & size, paint);
   
       paint.color = valueColor;
  
positive.code: }
  // TODO(jestelle) This should probably go somewhere else?  And maybe be more
  // general?
  class RepeatingCurveTween extends Animatable<double> {
    RepeatingCurveTween({ this.curve, this.repeats });
  
    Curve curve;
    int repeats;
  
negative.code:     Paint paint = new Paint()
        ..color = valueColor
        ..strokeWidth = _kCircularProgressIndicatorStrokeWidth
        ..style = PaintingStyle.stroke;
  
      if (value != null) {
        // Determinite
        double angle = value.clamp(0.0, 1.0) * _kSweep;
        Path path = new Path()
          ..arcTo(Point.origin & size, _kStartAngle, angle, false);
        canvas.drawPath(path, paint);
  
      } else {
        // Non-determinite
        paint.strokeCap = StrokeCap.square;
  
        double arcSweep = math.max(headValue * 3 / 2 * math.PI - tailValue * 3 / 2 * math.PI, _kEpsilon);
        Path path = new Path()
  