[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