Sync the Event, EventTarget and CustomEvent interfaces with the spec

Source/core/events/EventTarget.idl

Index: Source/core/events/EventTarget.idl
diff --git a/Source/core/events/EventTarget.idl b/Source/core/events/EventTarget.idl
index 6990a08f9697b89b5bc29c7582c3c565bbe82f42..b7279b3b81ab8dd3fc725b412b11831c66bfc1ed 100644
--- a/Source/core/events/EventTarget.idl
+++ b/Source/core/events/EventTarget.idl
@@ -18,6 +18,8 @@
  * Boston, MA 02110-1301, USA.
  */
 
+// https://dom.spec.whatwg.org/#interface-eventtarget
+
 [
     CheckSecurity=Window,
     Custom=ToV8,
@@ -26,11 +28,9 @@
 ] interface EventTarget {
     // FIXME: first 2 args should be required, but throwing TypeError breaks
     // legacy content.  http://crbug.com/353484
-    void addEventListener(optional DOMString? type,
-                          optional EventListener listener,
-                          optional boolean useCapture);
-    void removeEventListener(optional DOMString? type,
-                             optional EventListener listener,
-                             optional boolean useCapture);
+    // FIXME: type should not be nullable.
+    // FIXME: capture should have a default value false.
+    void addEventListener(optional DOMString? type, optional EventListener? listener, optional boolean capture);
+    void removeEventListener(optional DOMString? type, optional EventListener? listener, optional boolean capture);
     [RaisesException] boolean dispatchEvent(Event event);
 };