Remove some dead code in SVG "mixins"

third_party/WebKit/Source/core/svg/SVGMaskElement.h

 /*
  * Copyright (C) 2005 Alexander Kellett <lypanov@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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 32 matching lines @@
     SVGAnimatedLength* width() const { return m_width.get(); }
     SVGAnimatedLength* height() const { return m_height.get(); }
     SVGAnimatedEnumeration<SVGUnitTypes::SVGUnitType>* maskUnits() { return m_maskUnits.get(); }
     SVGAnimatedEnumeration<SVGUnitTypes::SVGUnitType>* maskContentUnits() { return m_maskContentUnits.get(); }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit SVGMaskElement(Document&);
 
-    bool isValid() const override { return SVGTests::isValid(document()); }
+    bool isValid() const override { return SVGTests::isValid(); }
     bool needsPendingResourceHandling() const override { return false; }
 
     bool isPresentationAttribute(const QualifiedName&) const override;
     bool isPresentationAttributeWithSVGDOM(const QualifiedName&) const override;
     void collectStyleForPresentationAttribute(const QualifiedName&, const AtomicString&, MutableStylePropertySet*) override;
     void svgAttributeChanged(const QualifiedName&) override;
     void childrenChanged(const ChildrenChange&) override;
 
     LayoutObject* createLayoutObject(const ComputedStyle&) override;
 
     bool selfHasRelativeLengths() const override;
 
     RefPtrWillBeMember<SVGAnimatedLength> m_x;
     RefPtrWillBeMember<SVGAnimatedLength> m_y;
     RefPtrWillBeMember<SVGAnimatedLength> m_width;
     RefPtrWillBeMember<SVGAnimatedLength> m_height;
     RefPtrWillBeMember<SVGAnimatedEnumeration<SVGUnitTypes::SVGUnitType>> m_maskUnits;
     RefPtrWillBeMember<SVGAnimatedEnumeration<SVGUnitTypes::SVGUnitType>> m_maskContentUnits;
 };
 
 } // namespace blink
 
 #endif // SVGMaskElement_h