[Form] Fixed memory leak in FormValidator
[Form] Added method Form::getClickedButton() to remove memory leak in FormValidator
bug #9211 [Form] Fixed memory leak in FormValidator (bschussek)

This PR was merged into the 2.3 branch.

Discussion
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[Form] Fixed memory leak in FormValidator

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9187
| License       | MIT
| Doc PR        | -

Commits
-------

1bb7e4d [Form] Added method Form::getClickedButton() to remove memory leak in FormValidator
5329ab5 [Form] Fixed memory leak in FormValidator
Merge branch '2.3'

* 2.3: (24 commits)
  Add german translation for several validators (Greater/Equal/Less)
  No Entity Manager defined exception
  fixed CS
  [Acl] Fix for issue #9433
  [Validator] fix docblock typos
  [DependencyInjection] removed the unused Reference and Parameter classes use statements from the compiled container class
  Removed useless check if self::$trustProxies is set
  Fix mistake in translation's service definition.
  if handler_id is identical to null fix
  CS fix
  Fixed ModelChoiceList tests in Propel1 bridge.
  [AclProvider] Fix incorrect behaviour when partial results returned from cache
  Check if the pipe array is empty before calling stream_select()
  [Intl] fixed datetime test as described in #9455
  bumped Symfony version to 2.3.8
  updated VERSION for 2.3.7
  updated CHANGELOG for 2.3.7
  re-factor Propel1 ModelChoiceList
  [Form] Added method Form::getClickedButton() to remove memory leak in FormValidator
  [Locale] fixed the failing test described in #9455
  ...

Conflicts:
	src/Symfony/Bridge/Propel1/Form/ChoiceList/ModelChoiceList.php
	src/Symfony/Bridge/Propel1/Tests/Fixtures/ItemQuery.php
	src/Symfony/Bridge/Propel1/Tests/Form/ChoiceList/ModelChoiceListTest.php
	src/Symfony/Bridge/Propel1/Tests/Propel1TestCase.php
	src/Symfony/Component/Form/Tests/CompoundFormTest.php
	src/Symfony/Component/HttpKernel/Kernel.php
	src/Symfony/Component/Process/Process.php