bug #11113 [HttpKernel] Fix event dispatcher dependency (hacfi)

This PR was merged into the 2.5 branch.

Discussion
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[HttpKernel] Fix event dispatcher dependency

Update composer.json to account for #9792.

[Symfony\Component\HttpKernel\DependencyInjection\RegisterListenersPass](https://github.com/symfony/symfony/blob/2.5/src/Symfony/Component/HttpKernel/DependencyInjection/RegisterListenersPass.php#L14) extends `Symfony\Component\EventDispatcher\DependencyInjection\RegisterListenersPass` which exists only in 2.5

Commits
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3d2dd81 [HttpKernel] Fix event dispatcher dependency

src/Symfony/Component/HttpKernel/composer.json

@@ -17,7 +17,7 @@
     ],
     "require": {
         "php": ">=5.3.3",
-        "symfony/event-dispatcher": "~2.1",
+        "symfony/event-dispatcher": "~2.5",
         "symfony/http-foundation": "~2.4",
         "symfony/debug": "~2.5",
         "psr/log": "~1.0"