Fix step timing outside range [0,1]

cc/animation/timing_function.cc

 // Copyright 2012 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 "cc/animation/timing_function.h"
 
 #include <memory>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ skipping 91 matching lines @@
   *min = 0.0f;
   *max = 1.0f;
 }
 
 float StepsTimingFunction::Velocity(double x) const {
   return 0.0f;
 }
 
 double StepsTimingFunction::GetPreciseValue(double t) const {
   const double steps = static_cast<double>(steps_);
-  return MathUtil::ClampToRange(
-      std::floor((steps * t) + GetStepsStartOffset()) / steps, 0.0, 1.0);
+  double current_step = std::floor((steps * t) + GetStepsStartOffset());
+  if (t >= 0 && current_step < 0)
+    current_step = 0;
+  if (t <= 1 && current_step > steps)
+    current_step = steps;
+  return current_step / steps;
 }
 
 float StepsTimingFunction::GetStepsStartOffset() const {
   switch (step_position_) {
     case StepPosition::START:
       return 1;
     case StepPosition::MIDDLE:
       return 0.5;
     case StepPosition::END:
       return 0;
     default:
       NOTREACHED();
       return 1;
   }
 }
 
 }  // namespace cc