Bug 1576453 - Fix a problem with unused variable in non-nightly builds; r=asuth

Differential Revision: https://phabricator.services.mozilla.com/D43357

--HG--
extra : moz-landing-system : lando

dom/quota/ActorsParent.cpp

@@ -4274,7 +4274,9 @@ nsresult QuotaManager::LoadQuota() {
       NS_WARN_IF(NS_FAILED(LoadQuotaFromCache()))) {
     // A keeper to defer the return only in Nightly, so that the telemetry data
     // for whole profile can be collected.
+#ifdef NIGHTLY_BUILD
     nsresult statusKeeper = NS_OK;
+#endif
 
     for (const PersistenceType type : kBestEffortPersistenceTypes) {
       if (NS_WARN_IF(IsShuttingDown())) {