rv = NS_NewRDFElement(aNameSpaceID, aTag, getter_AddRefs(result));
rv = nsXULElement::Create(aNameSpaceID, aTag, getter_AddRefs(result));
XULDocumentImpl::CreateElement(PRInt32 aNameSpaceID,                               nsIAtom* aTag,                               nsIContent** aResult){    nsresult rv;    nsCOMPtr<nsIContent> result;    if (aNameSpaceID == kNameSpaceID_HTML) {        nsCOMPtr<nsIHTMLContent> element;        const PRUnichar *tagName;        aTag->GetUnicode(&tagName);        rv = gHTMLElementFactory->CreateInstanceByTag(tagName, getter_AddRefs(element));        if (NS_FAILED(rv)) return rv;        result = do_QueryInterface(element);        if (! result)            return NS_ERROR_UNEXPECTED;    }    else {        rv = NS_NewRDFElement(aNameSpaceID, aTag, getter_AddRefs(result));        if (NS_FAILED(rv)) return rv;    }    rv = result->SetDocument(this, PR_FALSE);    NS_ASSERTION(NS_SUCCEEDED(rv), "unable to set element's document");    if (NS_FAILED(rv)) return rv;    *aResult = result;    NS_ADDREF(*aResult);    return NS_OK;}