Allow assertions to be enabled in Blink Release builds.

Source/core/rendering/compositing/CompositedLayerMapping.h

 /*
  * Copyright (C) 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 157 matching lines @@
 
     void finishAccumulatingSquashingLayers(size_t nextSquashedLayerIndex);
     void updateRenderingContext();
     void updateShouldFlattenTransform();
 
     // GraphicsLayerClient interface
     virtual void notifyAnimationStarted(const GraphicsLayer*, double monotonicTime) OVERRIDE;
     virtual void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect& clip) OVERRIDE;
     virtual bool isTrackingRepaints() const OVERRIDE;
 
-#ifndef NDEBUG
+#if ENABLE(ASSERT)
     virtual void verifyNotPainting() OVERRIDE;
 #endif
 
     LayoutRect contentsBox() const;
 
     GraphicsLayer* layerForHorizontalScrollbar() const { return m_layerForHorizontalScrollbar.get(); }
     GraphicsLayer* layerForVerticalScrollbar() const { return m_layerForVerticalScrollbar.get(); }
     GraphicsLayer* layerForScrollCorner() const { return m_layerForScrollCorner.get(); }
 
     // Removes the overflow controls host layer from its parent and positions it
@@ skipping 225 matching lines @@
     unsigned m_isMainFrameRenderViewLayer : 1;
     unsigned m_requiresOwnBackingStoreForIntrinsicReasons : 1;
     unsigned m_requiresOwnBackingStoreForAncestorReasons : 1;
     unsigned m_backgroundLayerPaintsFixedRootBackground : 1;
     unsigned m_scrollingContentsAreEmpty : 1;
 };
 
 } // namespace WebCore
 
 #endif // CompositedLayerMapping_h