Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/html/shadow/ClearButtonElement.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
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 37 matching lines @@
     RefPtr<ClearButtonElement> element = adoptRef(new ClearButtonElement(document, clearButtonOwner));
     element->setShadowPseudoId(AtomicString("-webkit-clear-button", AtomicString::ConstructFromLiteral));
     element->setAttribute(idAttr, ShadowElementNames::clearButton());
     return element.release();
 }
 
 void ClearButtonElement::detach(const AttachContext& context)
 {
     if (m_capturing) {
         if (Frame* frame = document().frame())
-            frame->eventHandler().setCapturingMouseEventsNode(0);
+            frame->eventHandler().setCapturingMouseEventsNode(nullptr);
     }
     HTMLDivElement::detach(context);
 }
 
 void ClearButtonElement::releaseCapture()
 {
     if (!m_capturing)
         return;
 
     if (Frame* frame = document().frame()) {
-        frame->eventHandler().setCapturingMouseEventsNode(0);
+        frame->eventHandler().setCapturingMouseEventsNode(nullptr);
         m_capturing = false;
     }
 }
 
 void ClearButtonElement::defaultEventHandler(Event* event)
 {
     if (!m_clearButtonOwner) {
         if (!event->defaultHandled())
             HTMLDivElement::defaultEventHandler(event);
         return;
@@ skipping 11 matching lines @@
                 frame->eventHandler().setCapturingMouseEventsNode(this);
                 m_capturing = true;
             }
         }
         m_clearButtonOwner->focusAndSelectClearButtonOwner();
         event->setDefaultHandled();
     }
     if (event->type() == EventTypeNames::mouseup && event->isMouseEvent() && toMouseEvent(event)->button() == LeftButton) {
         if (m_capturing) {
             if (Frame* frame = document().frame()) {
-                frame->eventHandler().setCapturingMouseEventsNode(0);
+                frame->eventHandler().setCapturingMouseEventsNode(nullptr);
                 m_capturing = false;
             }
             if (hovered()) {
                 m_clearButtonOwner->clearValue();
                 event->setDefaultHandled();
             }
         }
     }
 
     if (!event->defaultHandled())
         HTMLDivElement::defaultEventHandler(event);
 }
 
 bool ClearButtonElement::isClearButtonElement() const
 {
     return true;
 }
 
 }