parentReflowState = &aParentReflowState;
parentReflowState = nsnull;
inline nsReflowState::nsReflowState(nsIFrame*            aFrame,                                    const nsReflowState& aParentReflowState,                                    const nsSize&        aMaxSize,                                    nsReflowReason       aReflowReason){  reason = aReflowReason;  reflowCommand = nsnull;  maxSize = aMaxSize;  parentReflowState = &aParentReflowState;  frame = aFrame;  widthConstraint = eReflowSize_Constrained;  heightConstraint = eReflowSize_Constrained;  minSize.width = 0;  minSize.height = 0;}