[DomCrawler] Fixed creating form objects from form nodes.
Merge branch '2.3' into 2.4

* 2.3:
  [Security] made code easier to understand, added some missing unit tests
  [DependencyInjection] fixed InlineServiceDefinitionsPass to not inline a service if it's part of the current definition (to avoid an infinite loop)
  [DomCrawler] Fixed creating form objects from form nodes.
  disabled php.ini changes when using HHVM in .travis.yml
  [Process] fixed HHVM support
  Add support for HHVM in the getting of the PHP executable
  [Security] fixed error 500 instead of 403 if previous exception is provided to AccessDeniedException