anchor.diff:  import 'material.dart';
   
   const Duration _kBottomSheetDuration = const Duration(milliseconds: 200);
  +const double _kMinFlingVelocity = 700.0;
  +const double _kFlingVelocityScale = 1.0 / 300.0;
   
   class _BottomSheet extends StatefulComponent {
     _BottomSheet({
  
positive.code:     );
    }
  
    void didPop([dynamic result]) {
      completer.complete(result);
      super.didPop(result);
    }
  }
  
  
negative.code:           child: new CustomOneChildLayout(
              delegate: _layout,
              token: _layout.childTop.value,
              child: new GestureDetector(
                onVerticalDragStart: _handleDragStart,
                onVerticalDragUpdate: _handleDragUpdate,
                onVerticalDragEnd: _handleDragEnd,
                child: new Material(child: config.child)
              )
            )
          );
        }
  