Remove some unused state from RenderLayerStackingNode

Source/core/rendering/RenderLayerStackingNode.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 38 matching lines @@
 #include "core/rendering/compositing/RenderLayerCompositor.h"
 #include "public/platform/Platform.h"
 
 namespace WebCore {
 
 // FIXME: This should not require RenderLayer. There is currently a cycle where
 // in order to determine if we shoulBeNormalFlowOnly() we have to ask the render
 // 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)
     , m_stackingParent(0)
 #endif
 {
     m_isNormalFlowOnly = shouldBeNormalFlowOnly();
 
     // Non-stacking contexts should have empty z-order lists. As this is already the case,
     // there is no need to dirty / recompute these lists.
@@ skipping 34 matching lines @@
 #if !ASSERT_DISABLED
     updateStackingParentForZOrderLists(0);
 #endif
 
     if (m_posZOrderList)
         m_posZOrderList->clear();
     if (m_negZOrderList)
         m_negZOrderList->clear();
     m_zOrderListsDirty = true;
 
-    m_descendantsAreContiguousInStackingOrderDirty = true;
-
     if (!renderer()->documentBeingDestroyed())
         compositor()->setCompositingLayersNeedRebuild();
 }
 
 void RenderLayerStackingNode::dirtyStackingContextZOrderLists()
 {
     RenderLayerStackingNode* stackingContextNode = ancestorStackingContextNode();
     if (stackingContextNode)
         stackingContextNode->dirtyZOrderLists();
 
@@ skipping 241 matching lines @@
         return ancestor->stackingNode();
     return 0;
 }
 
 RenderLayerModelObject* RenderLayerStackingNode::renderer() const
 {
     return m_layer->renderer();
 }
 
 } // namespace WebCore