Introduce a SVGUnknownElement class for unknown SVG elements

Source/core/svg/SVGGraphicsElement.h

 /*
  * Copyright (C) 2004, 2005, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 39 matching lines @@
     virtual void toClipPath(Path&);
     virtual RenderObject* createRenderer(RenderStyle*);
 
 protected:
     SVGGraphicsElement(const QualifiedName&, Document*, ConstructionType = CreateSVGElement);
 
     bool isSupportedAttribute(const QualifiedName&);
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
     virtual void svgAttributeChanged(const QualifiedName&);
 
-    virtual bool rendererIsNeeded(const NodeRenderingContext& context) OVERRIDE { return rendererIsNeededInternal(context); }
-
     BEGIN_DECLARE_ANIMATED_PROPERTIES(SVGGraphicsElement)
         DECLARE_ANIMATED_TRANSFORM_LIST(Transform, transform)
     END_DECLARE_ANIMATED_PROPERTIES
 
 private:
     virtual bool isSVGGraphicsElement() const OVERRIDE { return true; }
 
     // SVGTests
     virtual void synchronizeRequiredFeatures() { SVGTests::synchronizeRequiredFeatures(this); }
     virtual void synchronizeRequiredExtensions() { SVGTests::synchronizeRequiredExtensions(this); }
     virtual void synchronizeSystemLanguage() { SVGTests::synchronizeSystemLanguage(this); }
 
     // Used by <animateMotion>
     OwnPtr<AffineTransform> m_supplementalTransform;
 };
 
 inline SVGGraphicsElement* toSVGGraphicsElement(Node* node)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!node || node->isSVGElement());
     ASSERT_WITH_SECURITY_IMPLICATION(!node || toSVGElement(node)->isSVGGraphicsElement());
     return static_cast<SVGGraphicsElement*>(node);
 }
 
 } // namespace WebCore
 
 #endif // SVGGraphicsElement_h