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

Source/core/svg/SVGScriptElement.h

Index: Source/core/svg/SVGScriptElement.h
diff --git a/Source/core/svg/SVGScriptElement.h b/Source/core/svg/SVGScriptElement.h
index 5506669060fe5229564f5e90d52d5f2bb8b98e72..ab4e59154e6acc36de5d16833f74de3a83666d67 100644
--- a/Source/core/svg/SVGScriptElement.h
+++ b/Source/core/svg/SVGScriptElement.h
@@ -42,6 +42,8 @@ public:
     String type() const;
     void setType(const String&);
 
+    virtual void accept(Visitor* visitor) const OVERRIDE { SVGElement::accept(visitor); }
+
 private:
     SVGScriptElement(const QualifiedName&, const Handle<Document>&, bool wasInsertedByParser, bool alreadyStarted);