anchor.diff:    ///
     /// See [RendererBinding] for an example of how this function is used.
     void flushPaint() {
  -    Timeline.startSync('Paint', arguments: timelineWhitelistArguments);
  -    _debugDoingPaint = true;
  +    profile(() { Timeline.startSync('Paint', arguments: timelineWhitelistArguments); });
  +    assert(() {
  +      _debugDoingPaint = true;
  +      return true;
  +    }());
       try {
         final List<RenderObject> dirtyNodes = _nodesNeedingPaint;
         _nodesNeedingPaint = <RenderObject>[];
  
positive.code:     String joiner: '; ',
      DiagnosticLevel minLevel: DiagnosticLevel.debug,
    }) {
      final RenderObject debugPreviousActiveLayout = _debugActiveLayout;
      _debugActiveLayout = null;
      final String result = super.toStringShallow(joiner: joiner, minLevel: minLevel);
      _debugActiveLayout = debugPreviousActiveLayout;
      return result;
    }
  
  
negative.code:     String prefixOtherLines: '',
      DiagnosticLevel minLevel: DiagnosticLevel.debug,
    }) {
      RenderObject debugPreviousActiveLayout;
      assert(() {
        debugPreviousActiveLayout = _debugActiveLayout;
        _debugActiveLayout = null;
        return true;
      }());
      final String result = super.toStringDeep(
        prefixLineOne: prefixLineOne,
        prefixOtherLines: prefixOtherLines,
        minLevel: minLevel,
      );
      assert(() {
        _debugActiveLayout = debugPreviousActiveLayout;
        return true;
      }());
      return result;
    }
  
  