Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/svg/SVGElementInstance.cpp

 /*
  * Copyright (C) 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  * Copyright (C) 2011 Torch Mobile (Beijing) Co. Ltd. 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 100 matching lines @@
 
 SVGElementInstance::~SVGElementInstance()
 {
     // Call detach because we may be deleted directly if we are a child of a detached instance.
     detach();
 
 #ifndef NDEBUG
     instanceCounter.decrement();
 #endif
 
-    m_element = 0;
+    m_element = nullptr;
 }
 
 // It's important not to inline removedLastRef, because we don't want to inline the code to
 // delete an SVGElementInstance at each deref call site.
 void SVGElementInstance::removedLastRef()
 {
 #if SECURITY_ASSERT_ENABLED
     m_deletionHasBegun = true;
 #endif
     delete this;
 }
 
 void SVGElementInstance::detach()
 {
     // Clear all pointers. When the node is detached from the shadow DOM it should be removed but,
     // due to ref counting, it may not be. So clear everything to avoid dangling pointers.
 
     for (SVGElementInstance* node = firstChild(); node; node = node->nextSibling())
         node->detach();
 
     // Deregister as instance for passed element, if we haven't already.
     if (m_element->instancesForElement().contains(this))
         m_element->removeInstanceMapping(this);
     // DO NOT clear ref to m_element because JavaScriptCore uses it for garbage collection
 
-    m_shadowTreeElement = 0;
+    m_shadowTreeElement = nullptr;
 
     m_directUseElement = 0;
     m_correspondingUseElement = 0;
 
     removeDetachedChildrenInContainer<SVGElementInstance, SVGElementInstance>(*this);
 }
 
 PassRefPtr<SVGElementInstanceList> SVGElementInstance::childNodes()
 {
     return SVGElementInstanceList::create(this);
@@ skipping 105 matching lines @@
         m_targetElement->setInstanceUpdatesBlocked(true);
 }
 
 SVGElementInstance::InstanceUpdateBlocker::~InstanceUpdateBlocker()
 {
     if (m_targetElement)
         m_targetElement->setInstanceUpdatesBlocked(false);
 }
 
 }