Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/rendering/RenderFlowThread.cpp

 /*
  * Copyright (C) 2011 Adobe Systems Incorporated. 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.
@@ skipping 49 matching lines @@
 {
     RefPtr<RenderStyle> newStyle(RenderStyle::create());
     newStyle->inheritFrom(parentStyle);
     newStyle->setDisplay(BLOCK);
     newStyle->setPosition(AbsolutePosition);
     newStyle->setZIndex(0);
     newStyle->setLeft(Length(0, Fixed));
     newStyle->setTop(Length(0, Fixed));
     newStyle->setWidth(Length(100, Percent));
     newStyle->setHeight(Length(100, Percent));
-    newStyle->font().update(0);
+    newStyle->font().update(nullptr);
 
     return newStyle.release();
 }
 
 void RenderFlowThread::addRegionToThread(RenderRegion* renderRegion)
 {
     ASSERT(renderRegion);
     m_regionList.add(renderRegion);
     renderRegion->setIsValid(true);
 }
@@ skipping 589 matching lines @@
 {
     if (!m_renderFlowThread)
         return;
     RenderView* view = m_renderFlowThread->view();
     ASSERT(view->flowThreadController()->currentRenderFlowThread() == m_renderFlowThread);
     view->flowThreadController()->setCurrentRenderFlowThread(m_previousRenderFlowThread);
 }
 
 
 } // namespace WebCore