if (mMapped && (aSheet != mMapped->mSheet)) { mMapped->SetStyleSheet(aSheet); return UniqueMapped(aSheet);
if (mSheet && mUniqued) { mSheet->DropMappedAttributes(this);
HTMLAttributesImpl::SetStyleSheet(nsIHTMLStyleSheet* aSheet){  if (mMapped && (aSheet != mMapped->mSheet)) {    mMapped->SetStyleSheet(aSheet);    return UniqueMapped(aSheet);  }  return NS_OK;}