Updated SVGListPropertyHelper as per SVG2 Spec

Source/core/svg/SVGPathSegCurvetoCubicAbs.h

Index: Source/core/svg/SVGPathSegCurvetoCubicAbs.h
diff --git a/Source/core/svg/SVGPathSegCurvetoCubicAbs.h b/Source/core/svg/SVGPathSegCurvetoCubicAbs.h
index f33fbbd0cf7e103c686d2fa78b110af2b171e9bf..04835a544e7e9abc2e70b58dcc9559d817708ea2 100644
--- a/Source/core/svg/SVGPathSegCurvetoCubicAbs.h
+++ b/Source/core/svg/SVGPathSegCurvetoCubicAbs.h
@@ -34,6 +34,11 @@ public:
         return adoptRefWillBeNoop(new SVGPathSegCurvetoCubicAbs(element, x, y, x1, y1, x2, y2));
     }
 
+    PassRefPtrWillBeRawPtr<SVGPathSeg> clone() override
+    {
+        return adoptRefWillBeNoop(new SVGPathSegCurvetoCubicAbs(nullptr, x(), y(), x1(), y1(), x2(), y2()));
+    }
+
 private:
     SVGPathSegCurvetoCubicAbs(SVGPathElement* element, float x, float y, float x1, float y1, float x2, float y2)
         : SVGPathSegCurvetoCubic(element, x, y, x1, y1, x2, y2) { }