Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/loader/ProgressTracker.cpp

 /*
  * Copyright (C) 2007 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 81 matching lines @@
 {
     m_progressItems.clear();
 
     m_totalPageAndResourceBytesToLoad = 0;
     m_totalBytesReceived = 0;
     m_progressValue = 0;
     m_lastNotifiedProgressValue = 0;
     m_lastNotifiedProgressTime = 0;
     m_finalProgressChangedSent = false;
     m_numProgressTrackedFrames = 0;
-    m_originatingProgressFrame = 0;
+    m_originatingProgressFrame = nullptr;
 }
 
 void ProgressTracker::progressStarted(Frame* frame)
 {
     WTF_LOG(Progress, "Progress started (%p) - frame %p(\"%s\"), value %f, tracked frames %d, originating frame %p", this, frame, frame->tree().uniqueName().utf8().data(), m_progressValue, m_numProgressTrackedFrames, m_originatingProgressFrame.get());
 
     if (m_numProgressTrackedFrames == 0 || m_originatingProgressFrame == frame) {
         reset();
         m_progressValue = initialProgressValue;
         m_originatingProgressFrame = frame;
@@ skipping 120 matching lines @@
         return;
 
     // Adjust the total expected bytes to account for any overage/underage.
     long long delta = item->bytesReceived - item->estimatedLength;
     m_totalPageAndResourceBytesToLoad += delta;
 
     m_progressItems.remove(identifier);
 }
 
 }