Clean up BoxClipper

Source/core/layout/LayoutBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 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 562 matching lines @@
 
     // Elements such as the <input> field override this to specify that they are scrollable
     // outside the context of the CSS overflow style
     virtual bool isIntrinsicallyScrollable(ScrollbarOrientation orientation) const { return false; }
 
     bool hasUnsplittableScrollingOverflow() const;
     bool isUnsplittableForPagination() const;
 
     virtual LayoutRect localCaretRect(InlineBox*, int caretOffset, LayoutUnit* extraWidthToEndOfLine = nullptr) override;
 
-    virtual LayoutRect overflowClipRect(const LayoutPoint& location, OverlayScrollbarSizeRelevancy = IgnoreOverlayScrollbarSize);
+    virtual LayoutRect overflowClipRect(const LayoutPoint& location, OverlayScrollbarSizeRelevancy = IgnoreOverlayScrollbarSize) const;
     LayoutRect clipRect(const LayoutPoint& location);
     virtual bool hasControlClip() const { return false; }
     virtual LayoutRect controlClipRect(const LayoutPoint&) const { return LayoutRect(); }
 
     virtual void paintObject(const PaintInfo&, const LayoutPoint&) { ASSERT_NOT_REACHED(); }
     virtual void paintBoxDecorationBackground(const PaintInfo&, const LayoutPoint&);
     virtual void paintMask(const PaintInfo&, const LayoutPoint&);
     virtual void imageChanged(WrappedImagePtr, const IntRect* = nullptr) override;
 
     void logicalExtentAfterUpdatingLogicalWidth(const LayoutUnit& logicalTop, LogicalExtentComputedValues&);
@@ skipping 341 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != nullptr))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace blink
 
 #endif // LayoutBox_h