Remove PlayStateInternal from Animation::UnlimitedCurrentTimeInternal

PlayStateInternal is being phased out as it relies on an extended play
state that includes a non-spec-compliant pending state. This patch
cleans up the implementation of UnlimitedCurrentTimeInternal. The
DCHECK code was previously used as a sanity check to ensure that an
update to the timing calculations did not change the value of current
time. This check is no longer being performed. The unlimited time
may deviate from the current time for a finished animations since the
hold time is not being used in the calculation when a start time is
set and not paused.

Bug: 960944
Change-Id: Ie8bd77b8cf770dc79fa65a08ed66c88fd6327c81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1933123
Commit-Queue: Kevin Ellis <kevers@chromium.org>
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719210}

third_party/blink/renderer/core/animation/animation.cc

@@ -432,11 +432,8 @@ base::Optional<double> Animation::CurrentTimeInternal() const {
   return hold_time_ ? hold_time_ : CalculateCurrentTime();
 }
 
-base::Optional<double> Animation::UnlimitedCurrentTimeInternal() const {
-#if DCHECK_IS_ON()
-  CurrentTimeInternal();
-#endif
-  return PlayStateInternal() == kPaused || !start_time_
+base::Optional<double> Animation::UnlimitedCurrentTime() const {
+  return CalculateAnimationPlayState() == kPaused || !start_time_
              ? CurrentTimeInternal()
              : CalculateCurrentTime();
 }

third_party/blink/renderer/core/animation/animation.h

@@ -126,7 +126,7 @@ class CORE_EXPORT Animation : public EventTargetWithInlineData,
   void setCurrentTime(double new_current_time,
                       bool is_null,
                       ExceptionState& = ASSERT_NO_EXCEPTION);
-  base::Optional<double> UnlimitedCurrentTimeInternal() const;
+  base::Optional<double> UnlimitedCurrentTime() const;
 
   // https://drafts.csswg.org/web-animations/#play-states
   static const char* PlayStateString(AnimationPlayState);

third_party/blink/renderer/core/animation/css/css_animations.cc

@@ -406,7 +406,7 @@ void CSSAnimations::CalculateAnimationUpdate(CSSAnimationUpdate& update,
                   CreateKeyframeEffectModel(resolver, animating_element,
                                             element, &style, parent_style, name,
                                             keyframe_timing_function.get(), i),
-                  timing, is_paused, animation->UnlimitedCurrentTimeInternal()),
+                  timing, is_paused, animation->UnlimitedCurrentTime()),
               specified_timing, keyframes_rule,
               animation_data->PlayStateList());
           if (is_paused != was_paused)