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

Source/core/dom/Node.cpp

Index: Source/core/dom/Node.cpp
diff --git a/Source/core/dom/Node.cpp b/Source/core/dom/Node.cpp
index b58f536b87745e932c2a8744adeae7b3ac98e2c8..97f10ada36e81eb8a38061e789f8bbe02b1d3b38 100644
--- a/Source/core/dom/Node.cpp
+++ b/Source/core/dom/Node.cpp
@@ -2447,8 +2447,12 @@ void Node::trace(Visitor* visitor)
     visitor->trace(m_parentOrShadowHostNode);
     visitor->trace(m_previous);
     visitor->trace(m_next);
+    // rareData() and m_data.m_renderer share their storage. We have to trace
+    // only one of them.
     if (hasRareData())
         visitor->trace(rareData());
+    else
+        visitor->trace(m_data.m_renderer);
     visitor->trace(m_treeScope);
 #endif
     EventTarget::trace(visitor);