Bug 1928123 - CookieStore must check if the worker is already shutting down, r=asuth

Differential Revision: https://phabricator.services.mozilla.com/D227564

dom/cookiestore/CookieStoreNotificationWatcherWrapper.cpp

@@ -129,6 +129,11 @@ void CookieStoreNotificationWatcherWrapper::ResolvePromiseWhenNotified(
         workerPrivate, "CookieStoreNotificationWatcher::PromiseResolver",
         [resolver = RefPtr(resolver)]() { resolver->Run(); });
 
+    if (!strongWorkerRef) {
+      // The worker is already shutting down. Let's ignore this promise.
+      return;
+    }
+
     workerRef = new ThreadSafeWorkerRef(strongWorkerRef);
   }