Introduce a SVGUnknownElement class for unknown SVG elements

Source/core/svg/SVGFontFaceElement.h

 /*
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * 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.
  *
@@ skipping 43 matching lines @@
 
 private:
     SVGFontFaceElement(const QualifiedName&, Document*);
 
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
 
     virtual void childrenChanged(bool changedByParser = false, Node* beforeChange = 0, Node* afterChange = 0, int childCountDelta = 0);
     virtual InsertionNotificationRequest insertedInto(ContainerNode*) OVERRIDE;
     virtual void removedFrom(ContainerNode*) OVERRIDE;
 
+    virtual bool rendererIsNeeded(const NodeRenderingContext&) OVERRIDE { return false; }
+
     RefPtr<StyleRuleFontFace> m_fontFaceRule;
     SVGFontElement* m_fontElement;
 };
 
 inline SVGFontFaceElement* toSVGFontFaceElement(Node* node)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(SVGNames::font_faceTag));
     return static_cast<SVGFontFaceElement*>(node);
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(SVG_FONTS)
 #endif
 
 // vim:ts=4:noet