Revert "fix #937"

This reverts commit b76d2a7a.

lib/classes/JsonApi/Routes/Courseware/Authority.php

@@ -93,10 +93,6 @@ class Authority
             return false;
         }
 
-        if ($structural_element->range_type === 'user') {
-            return $structural_element->range_id === $user->id;
-        }
-
         $perm = $GLOBALS['perm']->have_studip_perm(
             $structural_element->course->config->COURSEWARE_EDITING_PERMISSION,
             $structural_element->course->id,