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

Source/core/svg/SVGFilterPrimitiveStandardAttributes.h

Index: Source/core/svg/SVGFilterPrimitiveStandardAttributes.h
diff --git a/Source/core/svg/SVGFilterPrimitiveStandardAttributes.h b/Source/core/svg/SVGFilterPrimitiveStandardAttributes.h
index b3352bf85053a934362ae4696e7bf60a8e7f8ea9..821c6618a493b9f38cd352787524ada790900dee 100644
--- a/Source/core/svg/SVGFilterPrimitiveStandardAttributes.h
+++ b/Source/core/svg/SVGFilterPrimitiveStandardAttributes.h
@@ -46,6 +46,8 @@ public:
     // Returns true, if the new value is different from the old one.
     virtual bool setFilterEffectAttribute(FilterEffect*, const QualifiedName&);
 
+    virtual void accept(Visitor* visitor) const OVERRIDE { SVGStyledElement::accept(visitor); }
+
 protected:
     SVGFilterPrimitiveStandardAttributes(const QualifiedName&, const Handle<Document>&);