Subtree caching implementation in blink-core

Source/core/layout/LayoutInline.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 1410 matching lines @@
     if (!container)
         container = this;
 
     FloatPoint absPos = container->localToAbsolute();
     region.bounds.setX(absPos.x() + region.bounds.x());
     region.bounds.setY(absPos.y() + region.bounds.y());
 
     regions.append(region);
 }
 
-void LayoutInline::invalidateDisplayItemClients(const LayoutBoxModelObject& paintInvalidationContainer) const
+void LayoutInline::invalidateDisplayItemClients(const LayoutBoxModelObject& paintInvalidationContainer)
 {
     LayoutBoxModelObject::invalidateDisplayItemClients(paintInvalidationContainer);
     for (InlineFlowBox* box = firstLineBox(); box; box = box->nextLineBox())
         paintInvalidationContainer.invalidateDisplayItemClientOnBacking(*box);
 }
 
 } // namespace blink