Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/rendering/RenderWidget.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 68 matching lines @@
             parent->addChild(child);
         else
             toScrollView(child->parent())->removeChild(child);
         return;
     }
     widgetNewParentMap().set(child, parent);
 }
 
 RenderWidget::RenderWidget(Element* element)
     : RenderReplaced(element)
-    , m_widget(0)
+    , m_widget(nullptr)
     // Reference counting is used to prevent the widget from being
     // destroyed while inside the Widget code, which might not be
     // able to handle that.
     , m_refCount(1)
 {
     ASSERT(element);
     frameView()->addWidget(this);
 }
 
 void RenderWidget::willBeDestroyed()
 {
     frameView()->removeWidget(this);
 
     if (AXObjectCache* cache = document().existingAXObjectCache()) {
         cache->childrenChanged(this->parent());
         cache->remove(this);
     }
 
-    setWidget(0);
+    setWidget(nullptr);
 
     RenderReplaced::willBeDestroyed();
 }
 
 void RenderWidget::destroy()
 {
     willBeDestroyed();
     clearNode();
     deref();
 }
@@ skipping 217 matching lines @@
 
 void RenderWidget::widgetPositionsUpdated()
 {
     if (!m_widget)
         return;
     m_widget->widgetPositionsUpdated();
 }
 
 void RenderWidget::clearWidget()
 {
-    m_widget = 0;
+    m_widget = nullptr;
 }
 
 bool RenderWidget::nodeAtPoint(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction action)
 {
     bool hadResult = result.innerNode();
     bool inside = RenderReplaced::nodeAtPoint(request, result, locationInContainer, accumulatedOffset, action);
 
     // Check to see if we are really over the widget itself (and not just in the border/padding area).
     if ((inside || result.isRectBasedTest()) && !hadResult && result.innerNode() == node())
         result.setIsOverWidget(contentBoxRect().contains(result.localPoint()));
     return inside;
 }
 
 CursorDirective RenderWidget::getCursor(const LayoutPoint& point, Cursor& cursor) const
 {
     if (widget() && widget()->isPluginView()) {
         // A plug-in is responsible for setting the cursor when the pointer is over it.
         return DoNotSetCursor;
     }
     return RenderReplaced::getCursor(point, cursor);
 }
 
 } // namespace WebCore