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

Source/core/svg/SVGViewElement.h

Index: Source/core/svg/SVGViewElement.h
diff --git a/Source/core/svg/SVGViewElement.h b/Source/core/svg/SVGViewElement.h
index a6864523a996f11338d41079acb9a457fc5fd5cf..77c4ff3ab3f540914e34ca2fefef07bf6b974867 100644
--- a/Source/core/svg/SVGViewElement.h
+++ b/Source/core/svg/SVGViewElement.h
@@ -47,6 +47,8 @@ public:
     SVGZoomAndPanType zoomAndPan() const { return m_zoomAndPan; }
     void setZoomAndPan(unsigned short zoomAndPan) { m_zoomAndPan = SVGZoomAndPan::parseFromNumber(zoomAndPan); }
 
+    virtual void accept(Visitor* visitor) const OVERRIDE { SVGStyledElement::accept(visitor); }
+
 private:
     SVGViewElement(const QualifiedName&, const Handle<Document>&);