Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/scroll/ScrollView.cpp

 /*
  * Copyright (C) 2006, 2007, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 63 matching lines @@
 void ScrollView::setHasHorizontalScrollbar(bool hasBar)
 {
     if (hasBar && !m_horizontalScrollbar) {
         m_horizontalScrollbar = createScrollbar(HorizontalScrollbar);
         addChild(m_horizontalScrollbar.get());
         didAddScrollbar(m_horizontalScrollbar.get(), HorizontalScrollbar);
         m_horizontalScrollbar->styleChanged();
     } else if (!hasBar && m_horizontalScrollbar) {
         willRemoveScrollbar(m_horizontalScrollbar.get(), HorizontalScrollbar);
         removeChild(m_horizontalScrollbar.get());
-        m_horizontalScrollbar = 0;
+        m_horizontalScrollbar = nullptr;
     }
 }
 
 void ScrollView::setHasVerticalScrollbar(bool hasBar)
 {
     if (hasBar && !m_verticalScrollbar) {
         m_verticalScrollbar = createScrollbar(VerticalScrollbar);
         addChild(m_verticalScrollbar.get());
         didAddScrollbar(m_verticalScrollbar.get(), VerticalScrollbar);
         m_verticalScrollbar->styleChanged();
     } else if (!hasBar && m_verticalScrollbar) {
         willRemoveScrollbar(m_verticalScrollbar.get(), VerticalScrollbar);
         removeChild(m_verticalScrollbar.get());
-        m_verticalScrollbar = 0;
+        m_verticalScrollbar = nullptr;
     }
 }
 
 PassRefPtr<Scrollbar> ScrollView::createScrollbar(ScrollbarOrientation orientation)
 {
     return Scrollbar::create(this, orientation, RegularScrollbar);
 }
 
 void ScrollView::setScrollbarModes(ScrollbarMode horizontalMode, ScrollbarMode verticalMode,
                                    bool horizontalLock, bool verticalLock)
@@ skipping 1019 matching lines @@
 int ScrollView::pageStep(ScrollbarOrientation orientation) const
 {
     int length = (orientation == HorizontalScrollbar) ? visibleWidth() : visibleHeight();
     int minPageStep = static_cast<float>(length) * minFractionToStepWhenPaging();
     int pageStep = std::max(minPageStep, length - maxOverlapBetweenPages());
 
     return std::max(pageStep, 1);
 }
 
 } // namespace WebCore