nsIFrame* result = 0; aFrame->FirstChild(mPresContext, nsnull, &result);
nsIFrame* result = aFrame->GetFirstChild(nsnull);
nsFocusIterator::GetFirstChild(nsIFrame* aFrame){  nsIFrame* result = 0;  aFrame->FirstChild(mPresContext, nsnull, &result);  if (result)    result = GetRealFrame(result);  if (result && IsPopupFrame(result))    result = GetNextSibling(result);  return result;}