Bug 1474898 - Fix typo in null-check. r=asuth

I probably should have caught this in review.

Differential Revision: https://phabricator.services.mozilla.com/D2078

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

dom/serviceworkers/ServiceWorker.cpp

@@ -62,7 +62,7 @@ ServiceWorker::Create(nsIGlobalObject* aOwner,
     NS_ENSURE_TRUE(reg, nullptr);
 
     RefPtr<ServiceWorkerInfo> info = reg->GetByDescriptor(aDescriptor);
-    NS_ENSURE_TRUE(reg, nullptr);
+    NS_ENSURE_TRUE(info, nullptr);
 
     inner = new ServiceWorkerImpl(info, reg);
   }