anchor.diff:      this.selected,
       this.labelColor,
       this.unselectedLabelColor,
  +    this.labelStyle,
  +    this.unselectedLabelStyle,
       @required this.child,
     }) : super(key: key, animation: animation);
   
  +  final TextStyle labelStyle;
  +  final TextStyle unselectedLabelStyle;
     final bool selected;
     final Color labelColor;
     final Color unselectedLabelColor;
  
positive.code:           selected: false,
            labelColor: config.labelColor,
            unselectedLabelColor: config.unselectedLabelColor,
            child: wrappedTabs[previousIndex],
          );
        } else {
  
negative.code:           selected: false,
            labelColor: config.labelColor,
            unselectedLabelColor: config.unselectedLabelColor,
            labelStyle: config.labelStyle,
            unselectedLabelStyle: config.unselectedLabelStyle,
            child: new _TabLabelBar(
              onPerformLayout: _saveTabOffsets,
              children:  wrappedTabs,
  