Avoid a SVG property list-induced leak (Oilpan).

Source/core/svg/SVGPathSeg.cpp

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 26 matching lines @@
 
 SVGPathSeg::SVGPathSeg(SVGPathElement* contextElement)
     : m_ownerList(nullptr)
     , m_contextElement(contextElement)
 {
 }
 
 DEFINE_TRACE(SVGPathSeg)
 {
     visitor->trace(m_ownerList);
-    visitor->trace(m_contextElement);
 }
 
 void SVGPathSeg::commitChange()
 {
     if (m_contextElement)
         toSVGPathElement(m_contextElement)->pathSegListChanged();
 }
 
 }