Events should have an initialized flag.

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 86461d98f0a7853cde6527ded0bac20f16c50ce8..58dab753fdac671aca75b33e8469f85db4a46631 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -3946,8 +3946,10 @@ Event* Document::createEvent(ExecutionContext* executionContext, const String& e
     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;