anchor.diff:    bool get debugDoingThisLayout => _debugDoingThisLayout;
     static RenderObject _debugActiveLayout = null;
     static RenderObject get debugActiveLayout => _debugActiveLayout;
  -  bool _debugDoingThisLayoutWithCallback = false;
     bool _debugMutationsLocked = false;
     bool _debugCanParentUseSize;
     bool get debugCanParentUseSize => _debugCanParentUseSize;
     bool get debugCanPerformMutations {
       RenderObject node = this;
       while (true) {
  -      if (node._debugDoingThisLayoutWithCallback)
  +      if (node._doingThisLayoutWithCallback)
           return true;
         if (node._debugMutationsLocked)
           return false;
  
positive.code:   bool _needsLayout = true;
    bool get needsLayout => _needsLayout;
    RenderObject _relayoutSubtreeRoot;
    Constraints _constraints;
    Constraints get constraints => _constraints;
    bool debugDoesMeetConstraints(); // override this in a subclass to verify that your state matches the constraints object
  
negative.code:   void invokeLayoutCallback(LayoutCallback callback) {
      assert(_debugMutationsLocked);
      assert(_debugDoingThisLayout);
      assert(!_doingThisLayoutWithCallback);
      _doingThisLayoutWithCallback = true;
      try {
        callback(constraints);
      } finally {
        _doingThisLayoutWithCallback = false;
      }
    }
  
    // when the parent has rotated (e.g. when the screen has been turned
  