Events should have an initialized flag.

third_party/WebKit/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 3928 matching lines @@
 {
     DCHECK(!eventFactories().contains(eventFactory.get()));
     eventFactories().add(std::move(eventFactory));
 }
 
 Event* Document::createEvent(ExecutionContext* executionContext, const String& eventType, ExceptionState& exceptionState)
 {
     Event* event = nullptr;
     for (const auto& factory : eventFactories()) {
         event = factory->create(executionContext, eventType);
-        if (event)
+        if (event) {
+            event->unsetInitializedFlag();

[tkent, 2016/05/02 00:19:27]

This code implements what the specification says as is.
https://dom.spec.whatwg.org/#dom-document-createevent

However, I don't think this is good for code readability and code encapsulation.
I'd like
 - Remove unsetInitializedFlag()
 - Initialize the flag with 'false' in the no-argument Event constructor.

[ramya.v, 2016/05/02 05:31:44]

Done.

             return event;
+        }
     }
     exceptionState.throwDOMException(NotSupportedError, "The provided event type ('" + eventType + "') is invalid.");
     return nullptr;
 }
 
 void Document::addMutationEventListenerTypeIfEnabled(ListenerType listenerType)
 {
     if (ContextFeatures::mutationEventsEnabled(this))
         addListenerType(listenerType);
 }
@@ skipping 1944 matching lines @@
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     Document::WeakDocumentSet& set = Document::liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().getString().utf8().data());
 }
 #endif