Merge branch '2.3' into 2.6

* 2.3:
  Minor fixes
  Towards 100% HHVM compat
  trigger event with right user (add test)
  [Security] Initialize SwitchUserEvent::targetUser on attemptExitUser
  [Form] Fixed: Data mappers always receive forms indexed by their names

Conflicts:
	src/Symfony/Component/Debug/Tests/ErrorHandlerTest.php
	src/Symfony/Component/Filesystem/Filesystem.php
	src/Symfony/Component/Process/Tests/AbstractProcessTest.php

Author: nicolas-grekas

Tests/Fixtures/includes/ProjectWithXsdExtensionInPhar.phar

@@ -44,4 +44,4 @@ public function getAlias()
 </xsd:schema>
 EOT
 );
-$phar->setStub('<?php require_once "phar://ProjectWithXsdExtensionInPhar.phar/ProjectWithXsdExtensionInPhar.php"; __HALT_COMPILER(); ?>');
+$phar->setStub('<?php Phar::mapPhar("ProjectWithXsdExtensionInPhar.phar"); require_once "phar://ProjectWithXsdExtensionInPhar.phar/ProjectWithXsdExtensionInPhar.php"; __HALT_COMPILER(); ?>');