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

Source/core/rendering/RenderBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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
@@ skipping 142 matching lines @@
     , m_beingDestroyed(false)
     , m_hasMarkupTruncation(false)
     , m_hasBorderOrPaddingLogicalWidthChanged(false)
     , m_hasOnlySelfCollapsingChildren(false)
     , m_descendantsWithFloatsMarkedForLayout(false)
 {
     // RenderBlockFlow calls setChildrenInline(true).
     // By default, subclasses do not have inline children.
 }
 
+void RenderBlock::trace(Visitor* visitor)
+{
+    visitor->trace(m_children);
+    RenderBox::trace(visitor);
+}
+
 static void removeBlockFromDescendantAndContainerMaps(RenderBlock* block, TrackedDescendantsMap*& descendantMap, TrackedContainerMap*& containerMap)
 {
     if (OwnPtr<TrackedRendererListHashSet> descendantSet = descendantMap->take(block)) {
         TrackedRendererListHashSet::iterator end = descendantSet->end();
         for (TrackedRendererListHashSet::iterator descendant = descendantSet->begin(); descendant != end; ++descendant) {
             TrackedContainerMap::iterator it = containerMap->find(*descendant);
             ASSERT(it != containerMap->end());
             if (it == containerMap->end())
                 continue;
             HashSet<RenderBlock*>* containerSet = it->value.get();
@@ skipping 870 matching lines @@
         if (child == m_children.lastChild())
             m_children.setLastChild(child->previousSibling());
 
         if (child->previousSibling())
             child->previousSibling()->setNextSibling(child->nextSibling());
         if (child->nextSibling())
             child->nextSibling()->setPreviousSibling(child->previousSibling());
     }
 
     child->children()->setFirstChild(0);
-    child->m_next = 0;
+    child->m_next = nullptr;
 
     // Remove all the information in the flow thread associated with the leftover anonymous block.
     child->removeFromRenderFlowThread();
 
     // RenderGrid keeps track of its children, we must notify it about changes in the tree.
     if (child->parent()->isRenderGrid())
         toRenderGrid(child->parent())->dirtyGrid();
 
     child->setParent(0);
     child->setPreviousSibling(0);
@@ skipping 3777 matching lines @@
 void RenderBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const RenderObject* obj) const
 {
     showRenderObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace blink