Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/accessibility/AXImageMapLink.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 19 matching lines @@
 #include "core/accessibility/AXImageMapLink.h"
 
 #include "core/accessibility/AXObjectCache.h"
 #include "core/accessibility/AXRenderObject.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
 AXImageMapLink::AXImageMapLink()
-    : m_areaElement(0)
-    , m_mapElement(0)
+    : m_areaElement(nullptr)
+    , m_mapElement(nullptr)
 {
 }
 
 AXImageMapLink::~AXImageMapLink()
 {
 }
 
 void AXImageMapLink::detachFromParent()
 {
     AXMockObject::detachFromParent();
-    m_areaElement = 0;
-    m_mapElement = 0;
+    m_areaElement = nullptr;
+    m_mapElement = nullptr;
 }
 
 PassRefPtr<AXImageMapLink> AXImageMapLink::create()
 {
     return adoptRef(new AXImageMapLink());
 }
 
 AXObject* AXImageMapLink::parentObject() const
 {
     if (m_parent)
@@ skipping 85 matching lines @@
     else
         renderer = m_mapElement->renderer();
 
     if (!renderer)
         return LayoutRect();
 
     return m_areaElement->computeRect(renderer);
 }
 
 } // namespace WebCore