[Validator] Fixed object initializers in 2.5 version of the Validator
bug #11410 [Validator] Fixed object initializers in 2.5 version of the Validator (webmozart)

This PR was merged into the 2.5 branch.

Discussion
----------

[Validator] Fixed object initializers in 2.5 version of the Validator

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11159
| License       | MIT
| Doc PR        | -

Object initializers were forgot in the 2.5 Validator API. This PR implements them.

A bug was fixed also in the old version which resulted in the initializers being called multiple times if an object was validated in multiple groups within the same validation run. This fix will be backported separately to older versions.

Commits
-------

ce04073 [Validator] Fixed object initializers in 2.5 version of the Validator
[FrameworkBundle] changed KernelTestCase::getKernelClass() to check $_SERVER['KERNEL_DIR'] before invoking getPhpUnitXmlDir()
bug #11370 [FrameworkBundle] avoid raising unexpected RuntimeException when specifying $_SERVER['KERNEL_DIR'] (iteman)

This PR was submitted for the master branch but it was merged into the 2.5 branch instead (closes #11370).

Discussion
----------

[FrameworkBundle] avoid raising unexpected RuntimeException when specifying $_SERVER['KERNEL_DIR']

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

Since v2.5.0 (exactly e778cf19cd60f677ead35d662f816adeaae429b4), all tests that use WebTestCase are to be errors "RuntimeException: Unable to guess the Kernel directory." even though $_SERVER['KERNEL_DIR'] is specified. This has been preventing another test runner (e.g. [MakeGood](https://github.com/piece/makegood)) from running tests for a Symfony application without overriding KernelTestCase::getPhpUnitXmlDir() as follows.

The bootstrap file for testing in the app directory:

```php
<?php
...
$_SERVER['KERNEL_DIR'] = __DIR__;
require_once dirname(__DIR__) . '/var/bootstrap.php.cache';
```

console output:

```console
PHPUnit 4.1.3 by Sebastian Bergmann.

EE

Acme\DemoBundle\Tests\Controller\DemoController
 [ ] Index
 [ ] Secure section

Time: 146 ms, Memory: 9.50Mb

There were 2 errors:

1) Acme\DemoBundle\Tests\Controller\DemoControllerTest::testIndex
RuntimeException: Unable to guess the Kernel directory.

/path/to/symfony-application/vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Test/KernelTestCase.php:56
/path/to/symfony-application/vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Test/KernelTestCase.php:103
/path/to/symfony-application/vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Test/KernelTestCase.php:156
/path/to/symfony-application/vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Test/KernelTestCase.php:137
/path/to/symfony-application/vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Test/WebTestCase.php:33
/path/to/symfony-application/src/Acme/DemoBundle/Tests/Controller/DemoControllerTest.php:11
/path/to/eclipse/plugins/com.piece_framework.makegood.stagehandtestrunner_3.1.0.v201407050319/resources/php/vendor/piece/stagehand-testrunner/src/Runner/PHPUnitRunner.php:81
/path/to/eclipse/plugins/com.piece_framework.makegood.stagehandtestrunner_3.1.0.v201407050319/resources/php/vendor/piece/stagehand-testrunner/src/Process/TestRunner.php:100
/path/to/eclipse/plugins/com.piece_framework.makegood.stagehandtestrunner_3.1.0.v201407050319/resources/php/vendor/piece/stagehand-testrunner/src/CLI/TestRunnerApplication/Command/PluginCommand.php:149
/path/to/symfony-application/vendor/symfony/symfony/src/Symfony/Component/Console/Command/Command.php:252
/path/to/symfony-application/vendor/symfony/symfony/src/Symfony/Component/Console/Application.php:887
/path/to/symfony-application/vendor/symfony/symfony/src/Symfony/Component/Console/Application.php:193
/path/to/symfony-application/vendor/symfony/symfony/src/Symfony/Component/Console/Application.php:124
...
```

Commits
-------

6f58674 [FrameworkBundle] changed KernelTestCase::getKernelClass() to check $_SERVER['KERNEL_DIR'] before invoking getPhpUnitXmlDir()
[Validator] Fixed memory leak in ValidatorBuilder
bug #11454 [Validator] Fixed memory leak in ValidatorBuilder (webmozart)

This PR was merged into the 2.5 branch.

Discussion
----------

[Validator] Fixed memory leak in ValidatorBuilder

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11236
| License       | MIT
| Doc PR        | -

In 23534ca6ab4a107a5e801e710fb3c07b1a8874d9, the following code was introduced in `ValidatorBuilder::getValidator()`:

```php
AnnotationRegistry::registerLoader(function ($class) {
    if (0 === strpos($class, __NAMESPACE__.'\\Constraints\\')) {
        $file = str_replace(__NAMESPACE__.'\\Constraints\\', __DIR__.'/Constraints/', $class).'.php';

        if (is_file($file)) {
            require_once $file;

            return true;
        }
    }

    return false;
});
```

`AnnotationRegistry::registerLoader()` stores all loaders in a global array. Every time that `getValidator()` is called, a new closure is put onto the loader stack, referencing `$this` (i.e. the ValidatorBuilder) and consequently preventing the ValidatorBuilder (and its references) from being garbage-collected.

The call to `registerLoader()` did not exist in 2.4 and I can't find a reason why it should be there. All tests are green without that code. I suppose I used it for debugging and then forgot to remove it again, so I'm removing it here.

Commits
-------

283387a [Validator] Fixed memory leak in ValidatorBuilder
[Validator] Made sure that context changes don't leak out of (Contextual)ValidatorInterface