Remove isSupportedAttribute in svg

Source/core/svg/SVGFEMorphologyElement.h

 /*
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 27 matching lines @@
     SVGAnimatedNumber* radiusX() { return m_radius->firstNumber(); }
     SVGAnimatedNumber* radiusY() { return m_radius->secondNumber(); }
     SVGAnimatedString* in1() { return m_in1.get(); }
     SVGAnimatedEnumeration<MorphologyOperatorType>* svgOperator() { return m_svgOperator.get(); }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit SVGFEMorphologyElement(Document&);
 
-    bool isSupportedAttribute(const QualifiedName&);
     virtual bool setFilterEffectAttribute(FilterEffect*, const QualifiedName&) override;
     virtual void svgAttributeChanged(const QualifiedName&) override;
     virtual PassRefPtrWillBeRawPtr<FilterEffect> build(SVGFilterBuilder*, Filter*) override;
 
     RefPtrWillBeMember<SVGAnimatedNumberOptionalNumber> m_radius;
     RefPtrWillBeMember<SVGAnimatedString> m_in1;
     RefPtrWillBeMember<SVGAnimatedEnumeration<MorphologyOperatorType>> m_svgOperator;
 };
 
 } // namespace blink
 
 #endif // SVGFEMorphologyElement_h