Remove some unused state from RenderLayerStackingNode

Source/core/rendering/RenderLayerStackingNode.cpp

Index: Source/core/rendering/RenderLayerStackingNode.cpp
diff --git a/Source/core/rendering/RenderLayerStackingNode.cpp b/Source/core/rendering/RenderLayerStackingNode.cpp
index f335b4bd269a3342f9d6e2c878267c68c83608cc..8133af3dc9e2166b2d6a430e7441cf833b136be0 100644
--- a/Source/core/rendering/RenderLayerStackingNode.cpp
+++ b/Source/core/rendering/RenderLayerStackingNode.cpp
@@ -56,8 +56,6 @@ namespace WebCore {
 // layer about some of its state.
 RenderLayerStackingNode::RenderLayerStackingNode(RenderLayer* layer)
     : m_layer(layer)
-    , m_descendantsAreContiguousInStackingOrder(false)
-    , m_descendantsAreContiguousInStackingOrderDirty(true)
     , m_normalFlowListDirty(true)
 #if !ASSERT_DISABLED
     , m_layerListMutationAllowed(true)
@@ -112,8 +110,6 @@ void RenderLayerStackingNode::dirtyZOrderLists()
         m_negZOrderList->clear();
     m_zOrderListsDirty = true;
 
-    m_descendantsAreContiguousInStackingOrderDirty = true;
-
     if (!renderer()->documentBeingDestroyed())
         compositor()->setCompositingLayersNeedRebuild();
 }