nsGenericHTMLContainerElement::ChildAt(PRInt32 aIndex, nsIContent*& aResult) const {   nsIContent *child = (nsIContent *)mChildren.SafeElementAt(aIndex); NS_IF_ADDREF(child); aResult = child;  return NS_OK; }
NS_IMETHOD ChildAt(PRInt32 aIndex, nsIContent*& aResult) const { aResult = nsnull; return NS_OK; }
nsGenericHTMLContainerElement::ChildAt(PRInt32 aIndex,                                       nsIContent*& aResult) const{  // I really prefer NOT to do this test on all ChildAt calls - perhaps we  // should add FastChildAt().  nsIContent *child = (nsIContent *)mChildren.SafeElementAt(aIndex);  NS_IF_ADDREF(child);  aResult = child;  return NS_OK;}