blink: Cleanup core class forward declarations

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google 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 17 matching lines @@
 #include "core/layout/BackgroundBleedAvoidance.h"
 #include "core/layout/ContentChangeType.h"
 #include "core/layout/LayoutObject.h"
 #include "core/page/scrolling/StickyPositionScrollingConstraints.h"
 #include "platform/geometry/LayoutRect.h"
 #include "wtf/PtrUtil.h"
 #include <memory>
 
 namespace blink {
 
-class LineLayoutBoxModel;
 class PaintLayer;
 class PaintLayerScrollableArea;
 
 enum PaintLayerType {
   NoPaintLayer,
   NormalPaintLayer,
   // A forced or overflow clip layer is required for bookkeeping purposes,
   // but does not force a layer to be self painting.
   OverflowClipPaintLayer,
   ForcedPaintLayer
@@ skipping 467 matching lines @@
   std::unique_ptr<PaintLayer> m_layer;
 
   std::unique_ptr<LayoutBoxModelObjectRareData> m_rareData;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBoxModelObject, isBoxModelObject());
 
 }  // namespace blink
 
 #endif  // LayoutBoxModelObject_h