Updated SVGListPropertyHelper as per SVG2 Spec

Source/core/svg/SVGPathSegCurvetoCubicSmoothRel.h

 /*
  * Copyright (C) 2004, 2005, 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2008 Rob Buis <buis@kde.org>
  * Copyright (C) 2013 Samsung Electronics. 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 16 matching lines @@
 namespace blink {
 
 class SVGPathSegCurvetoCubicSmoothRel final : public SVGPathSegCurvetoCubicSmooth {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassRefPtrWillBeRawPtr<SVGPathSegCurvetoCubicSmoothRel> create(SVGPathElement* element, float x, float y, float x2, float y2)
     {
         return adoptRefWillBeNoop(new SVGPathSegCurvetoCubicSmoothRel(element, x, y, x2, y2));
     }
 
+    PassRefPtrWillBeRawPtr<SVGPathSeg> clone() override
+    {
+        return adoptRefWillBeNoop(new SVGPathSegCurvetoCubicSmoothRel(nullptr, x(), y(), x2(), y2()));
+    }
+
 private:
     SVGPathSegCurvetoCubicSmoothRel(SVGPathElement* element, float x, float y, float x2, float y2)
         : SVGPathSegCurvetoCubicSmooth(element, x, y, x2, y2) { }
 
     virtual unsigned short pathSegType() const override { return PATHSEG_CURVETO_CUBIC_SMOOTH_REL; }
     virtual String pathSegTypeAsLetter() const override { return "s"; }
 };
 
 } // namespace blink
 
 #endif // SVGPathSegCurvetoCubicSmoothRel_h