NS_ASSERTION(nsFrameList(aParentFrame->GetFirstChild(listName)) .ContainsFrame(aChildFrame), "not in child list");
GetChildListNameFor(nsIPresContext* aPresContext,                    nsIFrame*       aParentFrame,                    nsIFrame*       aChildFrame,                    nsIAtom**       aListName){  nsIAtom*      listName;    // See if the frame is moved out of the flow  if (aChildFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) {    // Look at the style information to tell    const nsStyleDisplay* disp = aChildFrame->GetStyleDisplay();        if (NS_STYLE_POSITION_ABSOLUTE == disp->mPosition) {      listName = nsLayoutAtoms::absoluteList;    } else if (NS_STYLE_POSITION_FIXED == disp->mPosition) {      listName = nsLayoutAtoms::fixedList;    } else {      NS_ASSERTION(aChildFrame->GetStyleDisplay()->IsFloating(),                   "not a floated frame");      listName = nsLayoutAtoms::floatList;    }  } else {    listName = nsnull;  }  // Verify that the frame is actually in that child list#ifdef NS_DEBUG   nsIFrame* firstChild;  aParentFrame->FirstChild(aPresContext, listName, &firstChild);  nsFrameList frameList(firstChild);  NS_ASSERTION(frameList.ContainsFrame(aChildFrame), "not in child list");#endif  NS_IF_ADDREF(listName);  *aListName = listName;}