Updated SVGListPropertyHelper as per SVG2 Spec

Source/core/svg/SVGPathSegClosePath.h

Index: Source/core/svg/SVGPathSegClosePath.h
diff --git a/Source/core/svg/SVGPathSegClosePath.h b/Source/core/svg/SVGPathSegClosePath.h
index 6b844f0fd00101a9d94781f27abef9e3cf64b392..b988edfe67c3d2be38528bd4bfcca63a741b5c2a 100644
--- a/Source/core/svg/SVGPathSegClosePath.h
+++ b/Source/core/svg/SVGPathSegClosePath.h
@@ -33,6 +33,11 @@ public:
         return adoptRefWillBeNoop(new SVGPathSegClosePath(element));
     }
 
+    PassRefPtrWillBeRawPtr<SVGPathSeg> clone() override
+    {
+        return adoptRefWillBeNoop(new SVGPathSegClosePath(nullptr));
+    }
+
 private:
     SVGPathSegClosePath(SVGPathElement* element)
         : SVGPathSeg(element) { }