if (!aHasAlternateRel && mDocument && mPreferredSheet.IsEmpty()) {      mDocument->SetHeaderData(nsHTMLAtoms::headerDefaultStyle, aTitle);  return PR_FALSE; }  return !aTitle.Equals(mPreferredSheet, nsCaseInsensitiveStringComparator());
return PR_FALSE;
CSSLoaderImpl::IsAlternate(const nsAString& aTitle, PRBool aHasAlternateRel){  // A sheet is alternate if it has a nonempty title that doesn't match the  // currently selected style set.  But if there _is_ no currently selected  // style set, the sheet wasn't marked as an alternate explicitly, and aTitle  // is nonempty, we should select the style set corresponding to aTitle, since  // that's a preferred sheet.  if (aTitle.IsEmpty()) {    return PR_FALSE;  }    if (!aHasAlternateRel && mDocument && mPreferredSheet.IsEmpty()) {    // There's no preferred set yet, and we now have a sheet with a title.    // Make that be the preferred set.    // XXXbz maybe this should be checking IsVoid(), actually, since the    // preferred set can be explicitly set to the empty string.  Look into    // this.    mDocument->SetHeaderData(nsHTMLAtoms::headerDefaultStyle, aTitle);    // We're definitely not an alternate    return PR_FALSE;  }  return !aTitle.Equals(mPreferredSheet, nsCaseInsensitiveStringComparator());}