Oilpan: Prepare to move RenderObject and RenderObjectChildList to Oilpan heap.

Source/core/rendering/RenderListItem.cpp

 /**
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  *
  * 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 21 matching lines @@
 #include "core/rendering/RenderView.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/text/StringBuilder.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
 RenderListItem::RenderListItem(Element* element)
     : RenderBlockFlow(element)
-    , m_marker(0)
+    , m_marker(nullptr)
     , m_hasExplicitValue(false)
     , m_isValueUpToDate(false)
     , m_notInList(false)
 {
     setInline(false);
 }
 
+void RenderListItem::trace(Visitor* visitor)
+{
+    visitor->trace(m_marker);
+    RenderBlockFlow::trace(visitor);
+}
+
 void RenderListItem::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
 {
     RenderBlockFlow::styleDidChange(diff, oldStyle);
 
     if (style()->listStyleType() != NoneListStyle
         || (style()->listStyleImage() && !style()->listStyleImage()->errorOccurred())) {
         RefPtr<RenderStyle> newStyle = RenderStyle::create();
         // The marker always inherits from the list item, regardless of where it might end
         // up (e.g., in some deeply nested line box). See CSS3 spec.
         newStyle->inheritFrom(style());
         if (!m_marker)
             m_marker = RenderListMarker::createAnonymous(this);
         m_marker->setStyle(newStyle.release());
     } else if (m_marker) {
         m_marker->destroy();
-        m_marker = 0;
+        m_marker = nullptr;
     }
 }
 
 void RenderListItem::willBeDestroyed()
 {
     if (m_marker) {
         m_marker->destroy();
-        m_marker = 0;
+        m_marker = nullptr;
     }
     RenderBlockFlow::willBeDestroyed();
 }
 
 void RenderListItem::insertedIntoTree()
 {
     RenderBlockFlow::insertedIntoTree();
 
     updateListMarkerNumbers();
 }
@@ skipping 432 matching lines @@
             // assume that all the following ones have too.
             // This gives us the opportunity to stop here and avoid
             // marking the same nodes again.
             break;
         }
         item->updateValue();
     }
 }
 
 } // namespace blink