Implement "auto -> angle" animation on <marker> orient attribute.

Source/core/svg/SVGAngle.h

 /*
  * Copyright (C) 2004, 2005, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006 Rob Buis <buis@kde.org>
  * Copyright (C) Research In Motion Limited 2010. 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 75 matching lines @@
     void setValue(float);
     float value() const;
 
     void setValueInSpecifiedUnits(float valueInSpecifiedUnits) { m_valueInSpecifiedUnits = valueInSpecifiedUnits; }
     float valueInSpecifiedUnits() const { return m_valueInSpecifiedUnits; }
 
     void newValueSpecifiedUnits(SVGAngleType unitType, float valueInSpecifiedUnits);
     void convertToSpecifiedUnits(SVGAngleType unitType, ExceptionState&);
 
     SVGEnumeration<SVGMarkerOrientType>* orientType() { return m_orientType.get(); }
+    const SVGEnumeration<SVGMarkerOrientType>* orientType() const { return m_orientType.get(); }
     void orientTypeChanged();
 
     // SVGPropertyBase:
 
     PassRefPtr<SVGAngle> clone() const;
 
     virtual String valueAsString() const override;
     void setValueAsString(const String&, ExceptionState&);
 
     virtual void add(PassRefPtrWillBeRawPtr<SVGPropertyBase>, SVGElement*) override;
     virtual void calculateAnimatedValue(SVGAnimationElement*, float percentage, unsigned repeatCount, PassRefPtr<SVGPropertyBase> from, PassRefPtr<SVGPropertyBase> to, PassRefPtr<SVGPropertyBase> toAtEndOfDurationValue, SVGElement* contextElement) override;
     virtual float calculateDistance(PassRefPtr<SVGPropertyBase> to, SVGElement* contextElement) override;
 
     static AnimatedPropertyType classType() { return AnimatedAngle; }
 
 private:
     SVGAngle();
     SVGAngle(SVGAngleType, float, SVGMarkerOrientType);
 
+    void assign(const SVGAngle&);
+
     SVGAngleType m_unitType;
     float m_valueInSpecifiedUnits;
     RefPtr<SVGMarkerOrientEnumeration> m_orientType;
 };
 
 inline PassRefPtr<SVGAngle> toSVGAngle(PassRefPtr<SVGPropertyBase> passBase)
 {
     RefPtr<SVGPropertyBase> base = passBase;
     ASSERT(base->type() == SVGAngle::classType());
     return static_pointer_cast<SVGAngle>(base.release());
 }
 
 } // namespace blink
 
 #endif // SVGAngle_h