NS_IMETHOD GetNextInFlow(nsIFrame** aNextInFlow) const { *aNextInFlow = mNextInFlow; return NS_OK;
virtual nsIFrame* GetNextInFlow() const { return mNextInFlow;
  NS_IMETHOD GetNextInFlow(nsIFrame** aNextInFlow) const {    *aNextInFlow = mNextInFlow;    return NS_OK;  }