DevTools: Make getEventListeners() of Console API work for window.

Source/core/events/EventTarget.cpp

Index: Source/core/events/EventTarget.cpp
diff --git a/Source/core/events/EventTarget.cpp b/Source/core/events/EventTarget.cpp
index ed7b07085db46863bb0799f869ab9bc7d965420a..2b65bb20c0c7d40c3f12406c9184894f4565770a 100644
--- a/Source/core/events/EventTarget.cpp
+++ b/Source/core/events/EventTarget.cpp
@@ -363,6 +363,12 @@ const EventListenerVector& EventTarget::getEventListeners(const AtomicString& ev
     return *listenerVector;
 }
 
+Vector<AtomicString> EventTarget::eventTypes()
+{
+    EventTargetData* d = eventTargetData();
+    return d ? d->eventListenerMap.eventTypes() : Vector<AtomicString>();
+}
+
 void EventTarget::removeAllEventListeners()
 {
     EventTargetData* d = eventTargetData();