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

Source/core/animation/AnimationTest.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 "core/animation/Animation.h"
 
 #include "bindings/v8/Dictionary.h"
 #include "core/animation/AnimatableLength.h"
 #include "core/animation/AnimationClock.h"
 #include "core/animation/AnimationHelpers.h"
 #include "core/animation/AnimationTestHelper.h"
 #include "core/animation/DocumentTimeline.h"
 #include "core/animation/KeyframeEffectModel.h"
-#include "platform/animation/TimingFunctionTestHelper.h"
 
 #include <gtest/gtest.h>
 
 namespace WebCore {
 
 class AnimationAnimationTest : public ::testing::Test {
 protected:
     AnimationAnimationTest()
         : document(Document::create())
         , element(document->createElement("foo", ASSERT_NO_EXCEPTION))
@@ skipping 343 matching lines @@
     player->setCurrentTime(150);
     EXPECT_EQ(inf, animation->timeToForwardsEffectChange());
     EXPECT_EQ(0, animation->timeToReverseEffectChange());
 
     player->setCurrentTime(200);
     EXPECT_EQ(inf, animation->timeToForwardsEffectChange());
     EXPECT_EQ(50, animation->timeToReverseEffectChange());
 }
 
 } // namespace WebCore