Update ForceHorriblySlowRectMapping comment

Source/core/layout/LayoutView.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 227 matching lines @@
 
     OwnPtrWillBePersistent<PendingSelection> m_pendingSelection;
 
     // TODO(pdr): This is only temporarily here and will be moving
     // when the API to cc is specified.
     OwnPtr<const CompositedDisplayList> m_compositedDisplayList;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutView, isLayoutView());
 
-// Suspends the LayoutState cached offset and clipRect optimization. Used under transforms
-// that cannot be represented by LayoutState (common in SVG) and when manipulating the layout
-// tree during layout in ways that can trigger paint invalidation of a non-child (e.g. when a list item
-// moves its list marker around). Note that even when disabled, LayoutState is still used to
-// store layoutDelta.
+// Suspends the PaintInvalidationState cached offset and clipRect optimization. Used under transforms
+// that cannot be represented by PaintInvalidationState (common in SVG) and when paint invalidation
+// containers don't follow the common tree-walk algorithm (e.g. when an absolute positioned descendant
+// is nested under a relatively positioned inline-block child).
 class ForceHorriblySlowRectMapping {
     WTF_MAKE_NONCOPYABLE(ForceHorriblySlowRectMapping);
 public:
     ForceHorriblySlowRectMapping(const PaintInvalidationState* paintInvalidationState)
         : m_paintInvalidationState(paintInvalidationState)
         , m_didDisable(m_paintInvalidationState && m_paintInvalidationState->cachedOffsetsEnabled())
     {
         if (m_paintInvalidationState)
             m_paintInvalidationState->m_cachedOffsetsEnabled = false;
     }
 
     ~ForceHorriblySlowRectMapping()
     {
         if (m_didDisable)
             m_paintInvalidationState->m_cachedOffsetsEnabled = true;
     }
 private:
     const PaintInvalidationState* m_paintInvalidationState;
     bool m_didDisable;
 };
 
 } // namespace blink
 
 #endif // LayoutView_h