Web Animations: Allow timing inputs outside the range [0, 1]

Source/platform/animation/TimingFunction.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "platform/animation/TimingFunction.h"
 
+#include "wtf/MathExtras.h"
+
 namespace WebCore {
 
 String LinearTimingFunction::toString() const
 {
     return "linear";
 }
 
 double LinearTimingFunction::evaluate(double fraction, double) const
 {
     return fraction;
@@ skipping 15 matching lines @@
             String::numberToStringECMAScript(this->y1()) + ", " + String::numberToStringECMAScript(this->x2()) +
             ", " + String::numberToStringECMAScript(this->y2()) + ")";
     default:
         ASSERT_NOT_REACHED();
     }
     return "";
 }
 
 double CubicBezierTimingFunction::evaluate(double fraction, double accuracy) const
 {
-    ASSERT_WITH_MESSAGE(fraction >= 0 && fraction <= 1, "Web Animations not yet implemented: Timing function behavior outside the range [0, 1] is not yet specified");
     if (!m_bezier)
         m_bezier = adoptPtr(new UnitBezier(m_x1, m_y1, m_x2, m_y2));
     return m_bezier->solve(fraction, accuracy);
 }
 
 String StepsTimingFunction::toString() const
 {
     StringBuilder builder;
     switch (this->subType()) {
     case StepsTimingFunction::Start:
@@ skipping 17 matching lines @@
         builder.append(")");
         break;
     default:
         ASSERT_NOT_REACHED();
     }
     return builder.toString();
 }
 
 double StepsTimingFunction::evaluate(double fraction, double) const
 {
-    ASSERT_WITH_MESSAGE(fraction >= 0 && fraction <= 1, "Web Animations not yet implemented: Timing function behavior outside the range [0, 1] is not yet specified");
     double startOffset = 0;
     switch (m_stepAtPosition) {
     case StepAtStart:
         startOffset = 1;
         break;
     case StepAtMiddle:
         startOffset = 0.5;
         break;
     case StepAtEnd:
         startOffset = 0;
         break;
     default:
         ASSERT_NOT_REACHED();
         break;
     }
-    return std::min(1.0, floor((m_steps * fraction) + startOffset) / m_steps);
+    return clampTo(floor((m_steps * fraction) + startOffset) / m_steps, 0.0, 1.0);
 }
 
 // Equals operators
 bool operator==(const LinearTimingFunction& lhs, const TimingFunction& rhs)
 {
     return rhs.type() == TimingFunction::LinearFunction;
 }
 
 bool operator==(const CubicBezierTimingFunction& lhs, const TimingFunction& rhs)
 {
@@ skipping 42 matching lines @@
     return false;
 }
 
 // No need to define specific operator!= as they can all come via this function.
 bool operator!=(const TimingFunction& lhs, const TimingFunction& rhs)
 {
     return !(lhs == rhs);
 }
 
 } // namespace WebCore