Bug 1575335 - Avoid creating an extra copy of the file name URI when checking whether the currently running script is from a tracker; r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D42706

dom/xhr/XMLHttpRequestMainThread.cpp

@@ -2426,12 +2426,8 @@ void XMLHttpRequestMainThread::MaybeLowerChannelPriority() {
   }
 
   JSContext* cx = jsapi.cx();
-  nsAutoCString fileNameString;
-  if (!nsJSUtils::GetCallingLocation(cx, fileNameString)) {
-    return;
-  }
 
-  if (!doc->IsScriptTracking(fileNameString)) {
+  if (!doc->IsScriptTracking(cx)) {
     return;
   }