NS_PRECONDITION(nsnull != aResult, "null ptr"); if (nsnull == aResult) {
NS_PRECONDITION(aResult, "null ptr"); if (!aResult) {
NS_NewFrameImageLoader(nsIFrameImageLoader** aResult){  NS_PRECONDITION(nsnull != aResult, "null ptr");  if (nsnull == aResult) {    return NS_ERROR_NULL_POINTER;  }  nsFrameImageLoader* it = new nsFrameImageLoader();  if (nsnull == it) {    return NS_ERROR_OUT_OF_MEMORY;  }  return it->QueryInterface(kIFrameImageLoaderIID, (void**) aResult);}