*** DO NOT LAND *** Attempt to understand Regions complexity

Source/core/rendering/LayoutState.h

 /*
  * Copyright (C) 2007 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 18 matching lines @@
 #include "core/rendering/ColumnInfo.h"
 #include "platform/geometry/LayoutRect.h"
 #include "wtf/HashMap.h"
 #include "wtf/Noncopyable.h"
 
 namespace WebCore {
 
 class RenderBlockFlow;
 class RenderBox;
 class RenderObject;
-class RenderFlowThread;
 class ShapeInsideInfo;
 
 class LayoutState {
     WTF_MAKE_NONCOPYABLE(LayoutState);
 public:
     LayoutState()
         : m_clipped(false)
         , m_isPaginated(false)
         , m_pageLogicalHeightChanged(false)
 #if !ASSERT_DISABLED
@@ skipping 88 matching lines @@
     LayoutSize m_lineGridPaginationOrigin;
 
 #ifndef NDEBUG
     RenderObject* m_renderer;
 #endif
 };
 
 } // namespace WebCore
 
 #endif // LayoutState_h