fix for #80498. prevent assertion / js exception when expanding news server when offline.

sr=bienvenu

mailnews/news/src/nsNntpService.cpp

@@ -1433,9 +1433,12 @@ nsNntpService::UpdateCounts(nsINntpIncomingServer *aNntpServer, nsIMsgWindow *aM
 
 	// run the url to update the counts
     rv = RunNewsUrl(url, aMsgWindow, nsnull);
-	if (NS_FAILED(rv)) return rv;
 
-	return NS_OK;
+    // being offline is not an error.
+    if (NS_SUCCEEDED(rv) || (rv == NS_MSG_ERROR_OFFLINE)) {
+      return NS_OK;
+    }
+    return rv;
 }
 
 NS_IMETHODIMP