*aSheet = mSheet; NS_IF_ADDREF(*aSheet); return NS_OK;
if (!Rule()) { *aSheet = nsnull; return NS_OK; } nsCOMPtr<nsICSSStyleSheet> sheet; Rule()->GetParentStyleSheet(getter_AddRefs(sheet)); if (!sheet) { *aSheet = nsnull; return NS_OK; } return CallQueryInterface(sheet, aSheet);
CSSStyleRuleImpl::GetParentStyleSheet(nsICSSStyleSheet** aSheet){  *aSheet = mSheet;  NS_IF_ADDREF(*aSheet);  return NS_OK;}