Remove unneeded mutable keyword in some member variables

Source/core/svg/animation/SVGSMILElement.h

 /*
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 187 matching lines @@
         Active,
         Frozen
     };
 
     QualifiedName m_attributeName;
 
     ActiveState determineActiveState(SMILTime elapsed) const;
     float calculateAnimationPercentAndRepeat(SMILTime elapsed, unsigned& repeat) const;
     SMILTime calculateNextProgressTime(SMILTime elapsed) const;
 
-    mutable SVGElement* m_targetElement;
+    SVGElement* m_targetElement;
 
     Vector<Condition> m_conditions;
     bool m_syncBaseConditionsConnected;
     bool m_hasEndEventConditions;
 
     bool m_isWaitingForFirstInterval;
 
     typedef HashSet<SVGSMILElement*> TimeDependentSet;
     TimeDependentSet m_syncBaseDependents;
 
@@ skipping 31 matching lines @@
 {
     return node.hasTagName(SVGNames::setTag) || node.hasTagName(SVGNames::animateTag) || node.hasTagName(SVGNames::animateMotionTag)
         || node.hasTagName(SVGNames::animateTransformTag) || node.hasTagName((SVGNames::discardTag));
 }
 
 DEFINE_ELEMENT_TYPE_CASTS_WITH_FUNCTION(SVGSMILElement);
 
 }
 
 #endif // SVGSMILElement_h