Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/accessibility/AXTable.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 26 matching lines @@
 #include "core/html/HTMLTableCellElement.h"
 #include "core/html/HTMLTableElement.h"
 #include "core/rendering/RenderTableCell.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
 AXTable::AXTable(RenderObject* renderer)
     : AXRenderObject(renderer)
-    , m_headerContainer(0)
+    , m_headerContainer(nullptr)
     , m_isAXTable(true)
 {
 }
 
 AXTable::~AXTable()
 {
 }
 
 void AXTable::init()
 {
@@ skipping 249 matching lines @@
 }
 
 void AXTable::clearChildren()
 {
     AXRenderObject::clearChildren();
     m_rows.clear();
     m_columns.clear();
 
     if (m_headerContainer) {
         m_headerContainer->detachFromParent();
-        m_headerContainer = 0;
+        m_headerContainer = nullptr;
     }
 }
 
 void AXTable::addChildren()
 {
     if (!isAXTable()) {
         AXRenderObject::addChildren();
         return;
     }
 
@@ skipping 214 matching lines @@
     }
 
     // try the standard
     if (title.isEmpty())
         title = AXRenderObject::title();
 
     return title;
 }
 
 } // namespace WebCore