Updated UPGRADE-2.4.md

UPGRADE-2.4.md

@@ -7,3 +7,44 @@ Form
  * The constructor parameter `$precision` in `IntegerToLocalizedStringTransformer`
    is now ignored completely, because a precision does not make sense for
    integers.
+
+EventDispatcher
+----------------
+
+ * The `getDispatcher()` and `getName()` methods from `Symfony\Component\EventDispatcher\Event`
+   are deprecated, the event dispatcher instance and event name can be received in the listener call instead.
+
+    Before:
+
+    ```php
+    use Symfony\Component\EventDispatcher\Event;
+
+    class Foo
+    {
+        public function myFooListener(Event $event)
+        {
+            $dispatcher = $event->getDispatcher();
+            $eventName = $event->getName();
+            $dispatcher->dispatch('log', $event);
+
+            // ... more code
+       }
+    }
+    ```
+
+    After:
+
+    ```php
+    use Symfony\Component\EventDispatcher\Event;
+    use Symfony\Component\EventDispatcher\EventDispatcherInterface;
+
+    class Foo
+    {
+        public function myFooListener(Event $event, $eventName, EventDispatcherInterface $dispatcher)
+        {
+            $dispatcher->dispatch('log', $event);
+
+            // ... more code
+        }
+    }
+    ```