Bug 748701 - Followup: typo fix, forgot to set rv. r=me

content/base/src/nsObjectLoadingContent.cpp

@@ -524,7 +524,7 @@ nsresult nsObjectLoadingContent::IsPluginEnabledForType(const nsCString& aMIMETy
       return NS_ERROR_FAILURE;
     }
     nsCOMPtr<nsIDOMWindow> topWindow;
-    window->GetTop(getter_AddRefs(topWindow));
+    rv = window->GetTop(getter_AddRefs(topWindow));
     NS_ENSURE_SUCCESS(rv, rv);
     nsCOMPtr<nsIDOMDocument> topDocument;
     rv = topWindow->GetDocument(getter_AddRefs(topDocument));