Fix errors found by PHPStan

Test Plan: Ran `phpstan analyze -a autoload.php phabricator/src`.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, hach-que

Differential Revision: https://secure.phabricator.com/D17371

src/applications/policy/controller/PhabricatorPolicyExplainController.php

@@ -85,7 +85,7 @@ final class PhabricatorPolicyExplainController
       return null;
     }
 
-    if (!PhabricatorSpacesNamespaceQuery::getSpacesExist($viewer)) {
+    if (!PhabricatorSpacesNamespaceQuery::getSpacesExist()) {
       return null;
     }