Move NGLayoutOpportunityTreeNode off Oilpan

third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_tree_node.cc

Index: third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_tree_node.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_tree_node.cc b/third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_tree_node.cc
index b737001fb829c76a3479175dce47bdf1b6f29c5c..e844418bd63cf72c4ce3510e24b09f07647e293f 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_tree_node.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_tree_node.cc
@@ -28,10 +28,4 @@ String NGLayoutOpportunityTreeNode::ToString() const {
                             : "null");
 }
 
-DEFINE_TRACE(NGLayoutOpportunityTreeNode) {
-  visitor->trace(left);
-  visitor->trace(bottom);
-  visitor->trace(right);
-}
-
 }  // namespace blink