Update AbstractGrant.php

Temporarily removing check on empty scopes as causing issues for Passport users

Author: Sephster

src/Grant/AbstractGrant.php

@@ -242,10 +242,6 @@ public function validateScopes($scopes, $redirectUri = null)
             $validScopes[] = $scope;
         }
 
-        if (empty($validScopes)) {
-            throw OAuthServerException::invalidScope('', $redirectUri);
-        }
-
         return $validScopes;
     }