Merge branch '4.0'

* 4.0:
  [Form] Fixed ContextErrorException in FileType
  [DI] Fix handling of inlined definitions by ContainerBuilder
  [Security] remove unused variable
  [DI] Fix infinite loop when analyzing references
  [Lock][Process][FrameworkBundle] fix tests
  Display a nice error message if the form/serializer component is missing.
  [SecurityBundle] providerIds is undefined error when firewall provider is not specified
  [SecurityBundle] providerIds is undefined error when firewall provider is not specified
  [SecurityBundle] providerIds is undefined error when firewall provider is not specified
  Force phpunit-bridge update (bis)
  [Bridge/PhpUnit] Fix disabling global state preservation
  Incorrect dot on method loadChoices in upgrade doc

Author: nicolas-grekas

Http/Firewall/ContextListener.php

@@ -43,7 +43,6 @@ class ContextListener implements ListenerInterface
     private $dispatcher;
     private $registered;
     private $trustResolver;
-    private $logoutOnUserChange = true;
 
     /**
      * @param TokenStorageInterface                     $tokenStorage