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

Source/core/svg/SVGFECompositeElement.h

Index: Source/core/svg/SVGFECompositeElement.h
diff --git a/Source/core/svg/SVGFECompositeElement.h b/Source/core/svg/SVGFECompositeElement.h
index 5e3fbaa3034014c6113595de0c059b0b1ce820d4..b4cab4f59881d65cc6ff81428751f6d7618ca6f0 100644
--- a/Source/core/svg/SVGFECompositeElement.h
+++ b/Source/core/svg/SVGFECompositeElement.h
@@ -78,6 +78,8 @@ class SVGFECompositeElement : public SVGFilterPrimitiveStandardAttributes {
 public:
     static PassRefPtr<SVGFECompositeElement> create(const QualifiedName&, const Handle<Document>&);
 
+    virtual void accept(Visitor* visitor) const OVERRIDE { SVGFilterPrimitiveStandardAttributes::accept(visitor); }
+
 private:
     SVGFECompositeElement(const QualifiedName&, const Handle<Document>&);