[oilpan] Implement accept methods to trace the class hierarchy of SVGElement and all sub-classes.

Source/core/svg/SVGFETileElement.h

Index: Source/core/svg/SVGFETileElement.h
diff --git a/Source/core/svg/SVGFETileElement.h b/Source/core/svg/SVGFETileElement.h
index 22e8bbda4102edd8456418d92f0be3f463674f11..e50c338fa173553775b2f4a075237e4bbac43da1 100644
--- a/Source/core/svg/SVGFETileElement.h
+++ b/Source/core/svg/SVGFETileElement.h
@@ -31,6 +31,8 @@ class SVGFETileElement : public SVGFilterPrimitiveStandardAttributes {
 public:
     static PassRefPtr<SVGFETileElement> create(const QualifiedName&, const Handle<Document>&);
 
+    virtual void accept(Visitor* visitor) const OVERRIDE { SVGFilterPrimitiveStandardAttributes::accept(visitor); }
+
 private:
     SVGFETileElement(const QualifiedName&, const Handle<Document>&);