Fix 'Add to Dashboard' issue with builtins

Summary: Ref T5307. Actually check the built in query with query, not engine.

Test Plan: Try a builtin query, and a custom query when making a dashboard panel.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T5307

Differential Revision: https://secure.phabricator.com/D17521

src/applications/dashboard/controller/PhabricatorDashboardQueryPanelInstallController.php

@@ -29,7 +29,7 @@ final class PhabricatorDashboardQueryPanelInstallController
     $engine = $engines[$v_engine];
     $engine->setViewer($viewer);
     $good_query = false;
-    if ($engine->isBuiltinQuery($v_engine)) {
+    if ($engine->isBuiltinQuery($v_query)) {
       $good_query = true;
     } else {
       $saved_query = id(new PhabricatorSavedQueryQuery())