Bug 1979608. r=hsivonen

Differential Revision: https://phabricator.services.mozilla.com/D258859

dom/xslt/xslt/txNodeSorter.cpp

@@ -77,9 +77,10 @@ nsresult txNodeSorter::addSortElement(Expr* aSelectExpr, Expr* aLangExpr,
     if (aLangExpr) {
       rv = aLangExpr->evaluateToString(aContext, lang);
       NS_ENSURE_SUCCESS(rv, rv);
-    } else if (aContext->getContextNode()
-                   .OwnerDoc()
-                   ->ShouldResistFingerprinting(RFPTarget::JSLocale)) {
+    }
+    if (lang.IsEmpty() &&
+        aContext->getContextNode().OwnerDoc()->ShouldResistFingerprinting(
+            RFPTarget::JSLocale)) {
       CopyUTF8toUTF16(nsRFPService::GetSpoofedJSLocale(), lang);
     }