[HttpFoundation] Remove not existing class member

open() and close() SessionHandlerProxy method suse $this->active
that was removed from the parent AbstractProxy class after 2.8.

Session/Storage/Proxy/SessionHandlerProxy.php

@@ -42,22 +42,14 @@ public function __construct(\SessionHandlerInterface $handler)
      */
     public function open($savePath, $sessionName)
     {
-        $return = (bool) $this->handler->open($savePath, $sessionName);
-
-        if (true === $return) {
-            $this->active = true;
-        }
-
-        return $return;
+        return (bool) $this->handler->open($savePath, $sessionName);
     }
 
     /**
      * {@inheritdoc}
      */
     public function close()
     {
-        $this->active = false;
-
         return (bool) $this->handler->close();
     }