14 files declare their use of EventDispatcher

AbstractHasDispatcher.php in drupal/core/vendor/guzzle/common/Guzzle/Common/AbstractHasDispatcher.php
Config.php in drupal/core/lib/Drupal/Core/Config/Config.php
Definition of Drupal\Core\Config\Config.
ConfigFactory.php in drupal/core/lib/Drupal/Core/Config/ConfigFactory.php
Definition of Drupal\Core\Config\ConfigFactory.
EsiListenerTest.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/EventListener/EsiListenerTest.php
EventDataCollectorTest.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/DataCollector/EventDataCollectorTest.php
EventDispatcherTest.php in drupal/core/vendor/symfony/event-dispatcher/Symfony/Component/EventDispatcher/Tests/EventDispatcherTest.php
EventTest.php in drupal/core/vendor/symfony/event-dispatcher/Symfony/Component/EventDispatcher/Tests/EventTest.php
HttpKernelTest.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/HttpKernelTest.php
Request.php in drupal/core/vendor/guzzle/http/Guzzle/Http/Message/Request.php
ResponseListenerTest.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/EventListener/ResponseListenerTest.php
TestEventDispatcher.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/Fixtures/TestEventDispatcher.php
TestHttpKernel.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/TestHttpKernel.php
TestHttpKernel.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/HttpCache/TestHttpKernel.php
TestMultipleHttpKernel.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/HttpCache/TestMultipleHttpKernel.php