Allow assertions to be enabled in Blink Release builds.

Source/core/rendering/RenderLayerStackingNode.h

Index: Source/core/rendering/RenderLayerStackingNode.h
diff --git a/Source/core/rendering/RenderLayerStackingNode.h b/Source/core/rendering/RenderLayerStackingNode.h
index abe6b68c218b2a4f48152f35738e905f1d7cc819..9aee6fa63da0e1d8f59fd0198fd9db131210cf5d 100644
--- a/Source/core/rendering/RenderLayerStackingNode.h
+++ b/Source/core/rendering/RenderLayerStackingNode.h
@@ -95,7 +95,7 @@ public:
 
     RenderLayer* layer() const { return m_layer; }
 
-#if ASSERT_ENABLED
+#if ENABLE(ASSERT)
     bool layerListMutationAllowed() const { return m_layerListMutationAllowed; }
     void setLayerListMutationAllowed(bool flag) { m_layerListMutationAllowed = flag; }
 #endif
@@ -128,7 +128,7 @@ private:
     void rebuildZOrderLists();
     void collectLayers(OwnPtr<Vector<RenderLayerStackingNode*> >& posZOrderList, OwnPtr<Vector<RenderLayerStackingNode*> >& negZOrderList);
 
-#if ASSERT_ENABLED
+#if ENABLE(ASSERT)
     bool isInStackingParentZOrderLists() const;
     bool isInStackingParentNormalFlowList() const;
     void updateStackingParentForZOrderLists(RenderLayerStackingNode* stackingParent);
@@ -162,7 +162,7 @@ private:
     unsigned m_normalFlowListDirty: 1;
     unsigned m_isNormalFlowOnly : 1;
 
-#if ASSERT_ENABLED
+#if ENABLE(ASSERT)
     unsigned m_layerListMutationAllowed : 1;
     RenderLayerStackingNode* m_stackingParent;
 #endif
@@ -172,7 +172,7 @@ inline void RenderLayerStackingNode::clearZOrderLists()
 {
     ASSERT(!isStackingContext());
 
-#if ASSERT_ENABLED
+#if ENABLE(ASSERT)
     updateStackingParentForZOrderLists(0);
 #endif
 
@@ -194,7 +194,7 @@ inline void RenderLayerStackingNode::updateZOrderLists()
     rebuildZOrderLists();
 }
 
-#if ASSERT_ENABLED
+#if ENABLE(ASSERT)
 class LayerListMutationDetector {
 public:
     explicit LayerListMutationDetector(RenderLayerStackingNode* stackingNode)