if (NULL == aInstancePtr) {
NS_PRECONDITION(nsnull != aInstancePtrResult, "null pointer"); if (nsnull == aInstancePtrResult) {
nsDocLoaderImpl::QueryInterface(REFNSIID aIID, void** aInstancePtr){  if (NULL == aInstancePtr) {    return NS_ERROR_NULL_POINTER;  }  if (aIID.Equals(kIDocumentLoaderIID)) {    *aInstancePtr = (void*)(nsIDocumentLoader*)this;    AddRef();    return NS_OK;  }  if (aIID.Equals(kDocLoaderImplIID)) {    *aInstancePtr = (void*)this;    AddRef();    return NS_OK;  }  return NS_NOINTERFACE;}