anchor.diff:      this.minDeltaRadius: 0.0,
       this.maxDeltaRadius: double.INFINITY,
       this.minDeltaTheta: 0.0,
  -    this.maxDeltaTheta: kTwoPi});
  +    this.maxDeltaTheta: kTwoPi
  +  });
   
     const SectorConstraints.tight({ double deltaRadius: 0.0, double deltaTheta: 0.0 })
       : minDeltaRadius = deltaRadius,
  
positive.code:   double _padding;
    double get padding => _padding;
    void set padding(double value) {
      assert(value != null);
      if (_padding != value) {
        _padding = value;
  
negative.code:     double childRadius = radius + padding;
      double paddingTheta = math.atan(padding / (radius + outerDeltaRadius));
      double innerTheta = paddingTheta; // increments with each child
      double remainingDeltaTheta = constraints.maxDeltaTheta - (innerTheta + paddingTheta);
      RenderSector child = firstChild;
      while (child != null) {
        SectorConstraints innerConstraints = new SectorConstraints(
          maxDeltaRadius: innerDeltaRadius,
          maxDeltaTheta: remainingDeltaTheta
        );
        SectorDimensions childDimensions = child.getIntrinsicDimensions(innerConstraints, childRadius);
        innerTheta += childDimensions.deltaTheta;
        remainingDeltaTheta -= childDimensions.deltaTheta;
        assert(child.parentData is SectorChildListParentData);
        child = child.parentData.nextSibling;
        if (child != null) {
          innerTheta += paddingTheta;
          remainingDeltaTheta -= paddingTheta;
        }
      }
      return new SectorDimensions.withConstraints(constraints,
  