Oilpan: move SVG property hierarchy to the heap.

Source/core/svg/SVGMPathElement.h

Index: Source/core/svg/SVGMPathElement.h
diff --git a/Source/core/svg/SVGMPathElement.h b/Source/core/svg/SVGMPathElement.h
index 4c6043f3a97a7f41197fd71d671e901839bd327c..802e46759c0b7906f05636fcc814c27c7455c6f4 100644
--- a/Source/core/svg/SVGMPathElement.h
+++ b/Source/core/svg/SVGMPathElement.h
@@ -33,6 +33,7 @@ class SVGPathElement;
 class SVGMPathElement final : public SVGElement,
                               public SVGURIReference {
     DEFINE_WRAPPERTYPEINFO();
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(SVGMPathElement);
 public:
     DECLARE_NODE_FACTORY(SVGMPathElement);
 
@@ -42,6 +43,8 @@ public:
 
     void targetPathChanged();
 
+    virtual void trace(Visitor*) override;
+
 private:
     explicit SVGMPathElement(Document&);