[DomCrawler] [HttpFoundation] Make `Content-Type` attributes identification case-insensitive
Merge branch '2.2' into 2.3

* 2.2:
  fixed CS
  Fixed the error handling when decoding invalid XML to avoid a Warning
  [Form] Fixed: The "data" option is taken into account even if it is NULL
  [DomCrawler] [HttpFoundation] Make `Content-Type` attributes identification case-insensitive

Conflicts:
	src/Symfony/Component/Form/Extension/Core/Type/FormType.php