Remove isSupportedAttribute in svg

Source/core/svg/SVGLineElement.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006 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 26 matching lines @@
     SVGAnimatedLength* x1() const { return m_x1.get(); }
     SVGAnimatedLength* y1() const { return m_y1.get(); }
     SVGAnimatedLength* x2() const { return m_x2.get(); }
     SVGAnimatedLength* y2() const { return m_y2.get(); }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit SVGLineElement(Document&);
 
-    bool isSupportedAttribute(const QualifiedName&);
     virtual void svgAttributeChanged(const QualifiedName&) override;
 
     virtual bool selfHasRelativeLengths() const override;
 
     RefPtrWillBeMember<SVGAnimatedLength> m_x1;
     RefPtrWillBeMember<SVGAnimatedLength> m_y1;
     RefPtrWillBeMember<SVGAnimatedLength> m_x2;
     RefPtrWillBeMember<SVGAnimatedLength> m_y2;
 };
 
 } // namespace blink
 
 #endif // SVGLineElement_h