anchor.diff:        contents = new ClipOval(child: contents);
       } else if (kMaterialEdges[config.type] != null) {
         contents = new ClipRRect(
  -        borderRadius: kMaterialEdges[config.type],
  +        borderRadius: radius,
           child: contents
         );
       }
  
positive.code: 
    /// The typographical style to use for text within this material.
    final TextStyle textStyle;
  
    /// The ink controller from the closest instance of this class that
    /// encloses the given context.
  
negative.code:     this.elevation: 0,
      this.color,
      this.textStyle,
      this.borderRadius,
      this.child
    }) : super(key: key) {
      assert(type != null);
      assert(elevation != null);
      assert(type != MaterialType.circle || borderRadius == null);
    }
  
    /// The widget below this widget in the tree.
  