remove references to "Silex"

Author: a1812

Session/Storage/MockFileSessionStorage.php

@@ -114,9 +114,8 @@ public function save()
             $this->data = $data;
         }
 
-        // this is needed for Silex, where the session object is re-used across requests
-        // in functional tests. In Symfony, the container is rebooted, so we don't have
-        // this issue
+        // this is needed when the session object is re-used across multiple requests
+        // in functional tests.
         $this->started = false;
     }