Introduce toSVGAnimateElement(), and use it

Source/core/svg/SVGAnimationElement.cpp

 /*
  * Copyright (C) 2004, 2005 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Cameron McCormack <cam@mcc.id.au>
  * 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
@@ skipping 489 matching lines @@
 
     if (percent == 1 || valuesCount == 1) {
         from = m_values[valuesCount - 1];
         to = m_values[valuesCount - 1];
         effectivePercent = 1;
         return;
     }
 
     CalcMode calcMode = this->calcMode();
     if (hasTagName(SVGNames::animateTag) || hasTagName(SVGNames::animateColorTag)) {
-        SVGAnimateElement* animateElement = static_cast<SVGAnimateElement*>(this);
-        AnimatedPropertyType attributeType = animateElement->determineAnimatedPropertyType(targetElement());
+        AnimatedPropertyType attributeType = toSVGAnimateElement(this)->determineAnimatedPropertyType(targetElement());
         // Fall back to discrete animations for Strings.
         if (attributeType == AnimatedBoolean
             || attributeType == AnimatedEnumeration
             || attributeType == AnimatedPreserveAspectRatio
             || attributeType == AnimatedString)
             calcMode = CalcModeDiscrete;
     }
     if (!m_keyPoints.isEmpty() && calcMode != CalcModePaced)
         return currentValuesFromKeyPoints(percent, effectivePercent, from, to);
 
@@ skipping 173 matching lines @@
     SVGSMILElement::setAttributeName(attributeName);
     checkInvalidCSSAttributeType(targetElement());
 }
 
 void SVGAnimationElement::checkInvalidCSSAttributeType(SVGElement* target)
 {
     m_hasInvalidCSSAttributeType = target && hasValidAttributeName() && attributeType() == AttributeTypeCSS && !isTargetAttributeCSSProperty(target, attributeName());
 }
 
 }