if (mLast) { #ifdef DEBUG nsresult rv = #endif PositionAt(mLast);  NS_ASSERTION(NS_SUCCEEDED(rv), "Failed to position iterator!"); }  mIsDone = mLast == nsnull;
mCurNode = mLast;
nsContentIterator::Last(){  NS_ASSERTION(mLast, "No last node!");  if (mLast) {#ifdef DEBUG    nsresult rv =#endif    PositionAt(mLast);    NS_ASSERTION(NS_SUCCEEDED(rv), "Failed to position iterator!");  }  mIsDone = mLast == nsnull;}