Remove isSupportedAttribute in svg

Source/core/svg/SVGGradientElement.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 38 matching lines @@
 
     SVGAnimatedTransformList* gradientTransform() { return m_gradientTransform.get(); }
     SVGAnimatedEnumeration<SVGSpreadMethodType>* spreadMethod() { return m_spreadMethod.get(); }
     SVGAnimatedEnumeration<SVGUnitTypes::SVGUnitType>* gradientUnits() { return m_gradientUnits.get(); }
 
     DECLARE_VIRTUAL_TRACE();
 
 protected:
     SVGGradientElement(const QualifiedName&, Document&);
 
-    bool isSupportedAttribute(const QualifiedName&);
     virtual void svgAttributeChanged(const QualifiedName&) override;
 
 private:
     virtual bool needsPendingResourceHandling() const override final { return false; }
 
     virtual void childrenChanged(const ChildrenChange&) override final;
 
     RefPtrWillBeMember<SVGAnimatedTransformList> m_gradientTransform;
     RefPtrWillBeMember<SVGAnimatedEnumeration<SVGSpreadMethodType>> m_spreadMethod;
     RefPtrWillBeMember<SVGAnimatedEnumeration<SVGUnitTypes::SVGUnitType>> m_gradientUnits;
 };
 
 inline bool isSVGGradientElement(const SVGElement& element)
 {
     return element.hasTagName(SVGNames::radialGradientTag) || element.hasTagName(SVGNames::linearGradientTag);
 }
 
 DEFINE_SVGELEMENT_TYPE_CASTS_WITH_FUNCTION(SVGGradientElement);
 
 } // namespace blink
 
 #endif // SVGGradientElement_h