Revert r160071 "Web Animations: Implement AnimationClock and fix start time of animations"

Source/core/core.gypi

 {
     'variables': {
         'core_idl_files': [
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSHostRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSKeyframeRule.idl',
@@ skipping 548 matching lines @@
             'animation/AnimatableStrokeDasharrayList.h',
             'animation/AnimatableTransform.cpp',
             'animation/AnimatableTransform.h',
             'animation/AnimatableUnknown.h',
             'animation/AnimatableValue.cpp',
             'animation/AnimatableValue.h',
             'animation/AnimatableVisibility.cpp',
             'animation/AnimatableVisibility.h',
             'animation/Animation.cpp',
             'animation/Animation.h',
-            'animation/AnimationClock.h',
             'animation/AnimationEffect.h',
             'animation/AnimationStack.h',
             'animation/DocumentTimeline.cpp',
             'animation/DocumentTimeline.h',
             'animation/InertAnimation.cpp',
             'animation/InertAnimation.h',
             'animation/KeyframeAnimationEffect.cpp',
             'animation/KeyframeAnimationEffect.h',
             'animation/Player.cpp',
             'animation/Player.h',
@@ skipping 2984 matching lines @@
         'core_unittest_files': [
             'animation/AnimatableColorTest.cpp',
             'animation/AnimatableDoubleTest.cpp',
             'animation/AnimatableLengthTest.cpp',
             'animation/AnimatableNeutralTest.cpp',
             'animation/AnimatableStrokeDasharrayListTest.cpp',
             'animation/AnimatableUnknownTest.cpp',
             'animation/AnimatableValueTestHelper.cpp',
             'animation/AnimatableValueTestHelper.h',
             'animation/AnimatableValueTestHelperTest.cpp',
-            'animation/AnimationClockTest.cpp',
             'animation/DocumentTimelineTest.cpp',
             'animation/KeyframeAnimationEffectTest.cpp',
             'animation/PlayerTest.cpp',
             'animation/TimedItemCalculationsTest.cpp',
             'animation/TimedItemTest.cpp',
             'css/CSSParserValuesTest.cpp',
             'css/CSSCalculationValueTest.cpp',
             'css/CSSValueTestHelper.h',
             'fetch/ImageResourceTest.cpp',
             'fetch/MemoryCacheTest.cpp',
@@ skipping 71 matching lines @@
                 'bison_exe': 'bison',
                 # We specify a preprocess so it happens locally and won't get
                 # distributed to goma.
                 # FIXME: /usr/bin/gcc won't exist on OSX forever. We want to
                 # use /usr/bin/clang once we require Xcode 4.x.
                 'preprocessor': '--preprocessor "/usr/bin/gcc -E -P -x c++"'
               }],
          ],
     }
 }