Move create() methods from StylePropertySet to MutableStylePropertySet.

Source/core/svg/SVGElementRareData.h

 /*
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 61 matching lines @@
     SVGElement* correspondingElement() { return m_correspondingElement; }
     void setCorrespondingElement(SVGElement* correspondingElement) { m_correspondingElement = correspondingElement; }
 
     CSSCursorImageValue* cursorImageValue() const { return m_cursorImageValue; }
     void setCursorImageValue(CSSCursorImageValue* cursorImageValue) { m_cursorImageValue = cursorImageValue; }
 
     StylePropertySet* animatedSMILStyleProperties() const { return m_animatedSMILStyleProperties.get(); }
     StylePropertySet* ensureAnimatedSMILStyleProperties()
     {
         if (!m_animatedSMILStyleProperties)
-            m_animatedSMILStyleProperties = StylePropertySet::create(SVGAttributeMode);
+            m_animatedSMILStyleProperties = MutableStylePropertySet::create(SVGAttributeMode);
         return m_animatedSMILStyleProperties.get();
     }
 
     void destroyAnimatedSMILStyleProperties()
     {
         m_animatedSMILStyleProperties.clear();
     }
 
     RenderStyle* overrideComputedStyle(Element* element, RenderStyle* parentStyle)
     {
@@ skipping 21 matching lines @@
     bool m_instancesUpdatesBlocked : 1;
     bool m_useOverrideComputedStyle : 1;
     bool m_needsOverrideComputedStyleUpdate : 1;
     RefPtr<StylePropertySet> m_animatedSMILStyleProperties;
     RefPtr<RenderStyle> m_overrideComputedStyle;
 };
 
 }
 
 #endif