Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/accessibility/AXInlineTextBox.cpp

 /*
  * Copyright (C) 2013, Google 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 46 matching lines @@
 {
     return adoptRef(new AXInlineTextBox(inlineTextBox));
 }
 
 void AXInlineTextBox::init()
 {
 }
 
 void AXInlineTextBox::detach()
 {
-    m_inlineTextBox = 0;
+    m_inlineTextBox = nullptr;
     m_axObjectCache = 0;
     AXObject::detach();
 }
 
 LayoutRect AXInlineTextBox::elementRect() const
 {
     if (!m_inlineTextBox)
         return LayoutRect();
 
     return m_inlineTextBox->bounds();
@@ skipping 67 matching lines @@
     case AbstractInlineTextBox::TopToBottom:
         return AccessibilityTextDirectionTopToBottom;
     case AbstractInlineTextBox::BottomToTop:
         return AccessibilityTextDirectionBottomToTop;
     }
 
     return AccessibilityTextDirectionLeftToRight;
 }
 
 } // namespace WebCore