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

Source/core/svg/SVGFEColorMatrixElement.h

Index: Source/core/svg/SVGFEColorMatrixElement.h
diff --git a/Source/core/svg/SVGFEColorMatrixElement.h b/Source/core/svg/SVGFEColorMatrixElement.h
index d2dfab6d9a71184da698eb2194f24320fd9b0caa..114798d03256a0c3ce741da19ca06a2fd3442eb6 100644
--- a/Source/core/svg/SVGFEColorMatrixElement.h
+++ b/Source/core/svg/SVGFEColorMatrixElement.h
@@ -70,6 +70,8 @@ class SVGFEColorMatrixElement : public SVGFilterPrimitiveStandardAttributes {
 public:
     static PassRefPtr<SVGFEColorMatrixElement> create(const QualifiedName&, const Handle<Document>&);
 
+    virtual void accept(Visitor* visitor) const OVERRIDE { SVGFilterPrimitiveStandardAttributes::accept(visitor); }
+
 private:
     SVGFEColorMatrixElement(const QualifiedName&, const Handle<Document>&);