NS_PRECONDITION(0 != aInstancePtr, "null ptr"); if (NULL == aInstancePtr) {
NS_PRECONDITION(nsnull != aInstancePtrResult, "null pointer"); if (nsnull == aInstancePtrResult) {
nsBlockFrame::QueryInterface(const nsIID& aIID, void** aInstancePtr){  NS_PRECONDITION(0 != aInstancePtr, "null ptr");  if (NULL == aInstancePtr) {    return NS_ERROR_NULL_POINTER;  }  if (aIID.Equals(kBlockFrameCID)) {    *aInstancePtr = (void*) (this);    return NS_OK;  }  if (aIID.Equals(kIRunaroundIID)) {    *aInstancePtr = (void*) ((nsIRunaround*) this);    return NS_OK;  }  if (aIID.Equals(kIFloaterContainerIID)) {    *aInstancePtr = (void*) ((nsIFloaterContainer*) this);    return NS_OK;  }  return nsBlockFrameSuper::QueryInterface(aIID, aInstancePtr);}