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

Source/core/svg/SVGPathSegList.h

 /*
  * 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 147 matching lines @@
         Base::append(passNewItem);
     }
 
     void updateListFromByteStream();
     void invalidateList();
 
     // FIXME: This pointer should be removed after SVGPathSeg has a tear-off.
     //
     // SVGPathSegList is either owned by SVGAnimatedPath or SVGPathSegListTearOff.
     // Both keep |contextElement| alive, so this ptr is always valid.
-    RawPtrWillBeMember<SVGPathElement> m_contextElement;
+    GC_PLUGIN_IGNORE("528275")
+    SVGPathElement* m_contextElement;
 
     mutable OwnPtr<SVGPathByteStream> m_byteStream;
     bool m_listSyncedToByteStream;
 };
 
 inline PassRefPtrWillBeRawPtr<SVGPathSegList> toSVGPathSegList(PassRefPtrWillBeRawPtr<SVGPropertyBase> passBase)
 {
     RefPtrWillBeRawPtr<SVGPropertyBase> base = passBase;
     ASSERT(base->type() == SVGPathSegList::classType());
     return static_pointer_cast<SVGPathSegList>(base.release());
 }
 
 } // namespace blink
 
 #endif