Use a bitmask for SVG render object types

Source/core/rendering/svg/RenderSVGViewportContainer.h

Index: Source/core/rendering/svg/RenderSVGViewportContainer.h
diff --git a/Source/core/rendering/svg/RenderSVGViewportContainer.h b/Source/core/rendering/svg/RenderSVGViewportContainer.h
index b1b79ed5e31e884af09644e980def2370f11f773..97ebb43575cce16402143d3302c3b2fc9a2d960d 100644
--- a/Source/core/rendering/svg/RenderSVGViewportContainer.h
+++ b/Source/core/rendering/svg/RenderSVGViewportContainer.h
@@ -43,7 +43,7 @@ public:
     virtual void paint(PaintInfo&, const LayoutPoint&) OVERRIDE;
 
 private:
-    virtual bool isSVGViewportContainer() const { return true; }
+    virtual SVGType getSVGType() const OVERRIDE { return IsSVGViewportContainer; }
     virtual const char* renderName() const { return "RenderSVGViewportContainer"; }
 
     AffineTransform viewportTransform() const;