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

Source/core/svg/SVGFEConvolveMatrixElement.h

Index: Source/core/svg/SVGFEConvolveMatrixElement.h
diff --git a/Source/core/svg/SVGFEConvolveMatrixElement.h b/Source/core/svg/SVGFEConvolveMatrixElement.h
index d454ba7e49ac052a066ed36ce520ae41216151ec..0ac9b8d23ed8732d25f4df23ac37e56ffef41887 100644
--- a/Source/core/svg/SVGFEConvolveMatrixElement.h
+++ b/Source/core/svg/SVGFEConvolveMatrixElement.h
@@ -71,6 +71,8 @@ public:
     void setOrder(float orderX, float orderY);
     void setKernelUnitLength(float kernelUnitLengthX, float kernelUnitLengthY);
 
+    virtual void accept(Visitor* visitor) const OVERRIDE { SVGFilterPrimitiveStandardAttributes::accept(visitor); }
+
 private:
     SVGFEConvolveMatrixElement(const QualifiedName&, const Handle<Document>&);