if (mSheet && mUniqued) { mSheet->DropMappedAttributes(this);
if (mMapped && (aSheet != mMapped->mSheet)) { mMapped->SetStyleSheet(aSheet); return UniqueMapped(aSheet);
nsHTMLMappedAttributes::SetStyleSheet(nsIHTMLStyleSheet* aSheet){  if (mSheet && mUniqued) {    mSheet->DropMappedAttributes(this);  }  mSheet = aSheet;  // not ref counted  mUniqued = PR_FALSE;  return NS_OK;}