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

Source/core/svg/SVGFontFaceNameElement.h

Index: Source/core/svg/SVGFontFaceNameElement.h
diff --git a/Source/core/svg/SVGFontFaceNameElement.h b/Source/core/svg/SVGFontFaceNameElement.h
index d0b3bcc5765cfbdc4e8925ea29881d63d1d14c82..7ae86899d37a18f13d10622940158ad3e8c29022 100644
--- a/Source/core/svg/SVGFontFaceNameElement.h
+++ b/Source/core/svg/SVGFontFaceNameElement.h
@@ -33,6 +33,8 @@ public:
     
     Result<CSSFontFaceSrcValue> srcValue() const;
 
+    virtual void accept(Visitor* visitor) const OVERRIDE { SVGElement::accept(visitor); }
+
 private:
     SVGFontFaceNameElement(const QualifiedName&, const Handle<Document>&);
 };