Clamp shape-margin to zero

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 267 matching lines @@
 
     void addVisualEffectOverflow();
     LayoutRectOutsets computeVisualEffectOverflowOutsets() const;
     void addOverflowFromChild(LayoutBox* child) { addOverflowFromChild(child, child->locationOffset()); }
     void addOverflowFromChild(LayoutBox* child, const LayoutSize& delta);
     void clearLayoutOverflow();
     void clearAllOverflows() { m_overflow.clear(); }
 
     void updateLayerTransformAfterLayout();
 
+    LayoutUnit contentWidthExcludingScrollbar() const { return m_frameRect.width() - borderLeft() - borderRight() - paddingLeft() - paddingRight(); }
     LayoutUnit contentWidth() const { return clientWidth() - paddingLeft() - paddingRight(); }
     LayoutUnit contentHeight() const { return clientHeight() - paddingTop() - paddingBottom(); }
     LayoutSize contentSize() const { return LayoutSize(contentWidth(), contentHeight()); }
     LayoutUnit contentLogicalWidth() const { return style()->isHorizontalWritingMode() ? contentWidth() : contentHeight(); }
     LayoutUnit contentLogicalHeight() const { return style()->isHorizontalWritingMode() ? contentHeight() : contentWidth(); }
 
     // IE extensions. Used to calculate offsetWidth/Height.  Overridden by inlines (RenderFlow)
     // to return the remaining width on a given line (and the height of a single line).
     virtual LayoutUnit offsetWidth() const override { return m_frameRect.width(); }
     virtual LayoutUnit offsetHeight() const override { return m_frameRect.height(); }
@@ skipping 621 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != 0))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace blink
 
 #endif // LayoutBox_h