WheelEvent created using document.createEvent() is not properly initialized

Source/core/dom/WheelEvent.cpp

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2005, 2006, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Samsung Electronics. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 23 matching lines @@
     : deltaX(0)
     , deltaY(0)
     , deltaZ(0)
     , wheelDeltaX(0)
     , wheelDeltaY(0)
     , deltaMode(WheelEvent::DOM_DELTA_PIXEL)
 {
 }
 
 WheelEvent::WheelEvent()
-    : m_deltaMode(DOM_DELTA_PIXEL)
+    : m_deltaX(0)
+    , m_deltaY(0)
+    , m_deltaZ(0)
+    , m_deltaMode(DOM_DELTA_PIXEL)
     , m_directionInvertedFromDevice(false)
 {
     ScriptWrappable::init(this);
 }
 
 WheelEvent::WheelEvent(const AtomicString& type, const WheelEventInit& initializer)
     : MouseEvent(type, initializer)
     , m_deltaX(initializer.deltaX ? initializer.deltaX : initializer.wheelDeltaX)
     , m_deltaY(initializer.deltaY ? initializer.deltaY : initializer.wheelDeltaY)
     , m_deltaZ(initializer.deltaZ)
@@ skipping 87 matching lines @@
     return static_cast<WheelEvent*>(EventDispatchMediator::event());
 }
 
 bool WheelEventDispatchMediator::dispatchEvent(EventDispatcher* dispatcher) const
 {
     ASSERT(event());
     return EventDispatchMediator::dispatchEvent(dispatcher) && !event()->defaultHandled();
 }
 
 } // namespace WebCore