nsIFrame* child;
nsFrameContentIterator::PositionAt(nsIContent* aCurNode){  nsIFrame* child;  // Starting with the first child frame search for the child frame  // with the matching content object  mParentFrame->FirstChild(mPresContext, nsnull, &child);  while (child) {    if (child->GetContent() == aCurNode) {      break;    }    child = ::GetNextChildFrame(mPresContext, child);  }  if (child) {    // Make it the current child    mCurrentChild = child;    mIsDone = PR_FALSE;    return NS_OK;  }  return NS_ERROR_FAILURE;}