Bug 1258339 - check return value of GetFileSize. r=janv

MozReview-Commit-ID: Fy0jMfVpcCN

--HG--
extra : rebase_source : 31ac4fe714aa62a6c5b86438ca3ab983c7d4a6d9

dom/indexedDB/ActorsParent.cpp

@@ -10915,8 +10915,8 @@ UpdateRefcountFunction::Reset()
 
       if (aFileManager->EnforcingQuota()) {
         rv = file->GetFileSize(&fileSize);
-        if (NS_WARN_IF(!file)) {
-          return NS_ERROR_FAILURE;
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+          return rv;
         }
       }