[Security/Http] fix mock logger in test
Merge branch '2.7'

* 2.7:
  [Security/Http] fix mock logger in test
  [Serializer] Fix XmlFileLoader test
  [2.6] silence deprecation notices in new components
  [2.5] silence deprecation notices in new components
  [VarDumper] Minor fix for the uniformity
  [TwigBundle] added missing absolute URL in Twig exceptions