minor #8637 Added getSubscribedEvents() to UserLocaleSubscriber (cirrosol)

This PR was submitted for the 3.3 branch but it was merged into the 2.7 branch instead (closes #8637).

Discussion
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Added getSubscribedEvents() to UserLocaleSubscriber

The code wasn't working without this.

Commits
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78ec0c7 Added getSubscribedEvents() to UserLocaleSubscriber

Author: xabbuh

session/locale_sticky_session.rst

@@ -134,8 +134,10 @@ event:
     // src/AppBundle/EventListener/UserLocaleListener.php
     namespace AppBundle\EventListener;
 
+    use Symfony\Component\EventDispatcher\EventSubscriberInterface;
     use Symfony\Component\HttpFoundation\Session\Session;
     use Symfony\Component\Security\Http\Event\InteractiveLoginEvent;
+    use Symfony\Component\Security\Http\SecurityEvents;
 
     /**
      * Stores the locale of the user in the session after the
@@ -164,6 +166,13 @@ event:
                 $this->session->set('_locale', $user->getLocale());
             }
         }
+
+        public static function getSubscribedEvents()
+        {
+            return array(
+                SecurityEvents::INTERACTIVE_LOGIN => array(array('onInteractiveLogin', 15)),
+            );
+        }
     }
 
 Then register the listener: