Web Animations API: Implement step-middle and steps(x, middle) timing functions.

Source/core/css/CSSComputedStyleDeclaration.cpp

 /*
  * Copyright (C) 2004 Zack Rusin <zack@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2011 Sencha, Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
@@ skipping 999 matching lines @@
                 }
                 return cssValuePool().createIdentifierValue(valueId);
             }
             return CSSCubicBezierTimingFunctionValue::create(bezierTimingFunction->x1(), bezierTimingFunction->y1(), bezierTimingFunction->x2(), bezierTimingFunction->y2());
         }
 
     case TimingFunction::StepsFunction:
         {
             const StepsTimingFunction* stepsTimingFunction = toStepsTimingFunction(timingFunction);
             if (stepsTimingFunction->subType() == StepsTimingFunction::Custom)
-                return CSSStepsTimingFunctionValue::create(stepsTimingFunction->numberOfSteps(), stepsTimingFunction->stepAtStart());
+                return CSSStepsTimingFunctionValue::create(stepsTimingFunction->numberOfSteps(), stepsTimingFunction->stepAtPosition());
+
             CSSValueID valueId;
             switch (stepsTimingFunction->subType()) {
             case StepsTimingFunction::Start:
                 valueId = CSSValueStepStart;
                 break;
             case StepsTimingFunction::End:
                 valueId = CSSValueStepEnd;
                 break;
             default:
                 ASSERT_NOT_REACHED();
@@ skipping 2003 matching lines @@
     static const CSSPropertyID propertiesAfterSlashSeperator[3] = { CSSPropertyBackgroundSize, CSSPropertyBackgroundOrigin,
                                                                     CSSPropertyBackgroundClip };
 
     RefPtrWillBeRawPtr<CSSValueList> list = CSSValueList::createSlashSeparated();
     list->append(valuesForShorthandProperty(StylePropertyShorthand(CSSPropertyBackground, propertiesBeforeSlashSeperator, WTF_ARRAY_LENGTH(propertiesBeforeSlashSeperator))));
     list->append(valuesForShorthandProperty(StylePropertyShorthand(CSSPropertyBackground, propertiesAfterSlashSeperator, WTF_ARRAY_LENGTH(propertiesAfterSlashSeperator))));
     return list.release();
 }
 
 } // namespace WebCore