Use method registration approach for creating events on core and modules.

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 3904 matching lines @@
     ensureScriptedAnimationController().enqueuePerFrameEvent(scrollEvent.release());
 }
 
 void Document::enqueueResizeEvent()
 {
     RefPtrWillBeRawPtr<Event> event = Event::create(EventTypeNames::resize);
     event->setTarget(domWindow());
     ensureScriptedAnimationController().enqueuePerFrameEvent(event.release());
 }
 
+Document::EventFactorySet& Document::eventFactories()
+{
+    DEFINE_STATIC_LOCAL(EventFactorySet, s_eventFactory, ());
+    return s_eventFactory;
+}
+
+void Document::registerEventFactory(EventFactoryBase* eventFactory)
+{
+    ASSERT(!eventFactories().contains(eventFactory));
+    eventFactories().add(eventFactory);
+}
+
 PassRefPtrWillBeRawPtr<Event> Document::createEvent(const String& eventType, ExceptionState& exceptionState)
 {
-    RefPtrWillBeRawPtr<Event> event = EventFactory::create(eventType);
-    if (event)
-        return event.release();
-
+    RefPtrWillBeRawPtr<Event> event = nullptr;
+    for (EventFactorySet::const_iterator it = eventFactories().begin(); it != eventFactories().end(); ++it) {
+        event = (*it)->create(eventType);
+        if (event)
+            return event.release();
+    }
     exceptionState.throwDOMException(NotSupportedError, "The provided event type ('" + eventType + "') is invalid.");
     return nullptr;
 }
 
 void Document::addMutationEventListenerTypeIfEnabled(ListenerType listenerType)
 {
     if (ContextFeatures::mutationEventsEnabled(this))
         addListenerType(listenerType);
 }
 
@@ skipping 1860 matching lines @@
     visitor->trace(m_timeline);
     visitor->trace(m_compositorPendingAnimations);
     visitor->registerWeakMembers<Document, &Document::clearWeakMembers>(this);
     DocumentSupplementable::trace(visitor);
     TreeScope::trace(visitor);
     ContainerNode::trace(visitor);
     ExecutionContext::trace(visitor);
 }
 
 } // namespace WebCore