Remove usage of Timing::IsNull

Blink's animation doesn't use Timing::Nullvalue anymore, and this
CL removes the IsNUll.

Bug: 791086
Change-Id: I488f077b96ec6477176876f224f7f5e5d71c07ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2430484
Commit-Queue: Xida Chen <xidachen@chromium.org>
Reviewed-by: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811448}

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

@@ -626,7 +626,7 @@ void Animation::NotifyReady(double ready_time) {
 // Refer to Step 8.3 'pending play task' in
 // https://drafts.csswg.org/web-animations/#playing-an-animation-section.
 void Animation::CommitPendingPlay(double ready_time) {
-  DCHECK(!Timing::IsNull(ready_time));
+  DCHECK(std::isfinite(ready_time));
   DCHECK(start_time_ || hold_time_);
   DCHECK(pending_play_);
   pending_play_ = false;
@@ -1892,18 +1892,18 @@ void Animation::StartAnimationOnCompositor(
       start_time =
           start_time.value() - (EffectEnd() / fabs(EffectivePlaybackRate()));
     }
+    DCHECK(std::isfinite(start_time.value()));
   } else {
     base::Optional<double> current_time = CurrentTimeInternal();
     DCHECK(current_time);
     time_offset =
         reversed ? EffectEnd() - current_time.value() : current_time.value();
     time_offset = time_offset / fabs(EffectivePlaybackRate());
+    DCHECK(std::isfinite(time_offset));
   }
 
-  DCHECK(!start_time || !Timing::IsNull(start_time.value()));
   DCHECK_NE(compositor_group_, 0);
   DCHECK(To<KeyframeEffect>(content_.Get()));
-  DCHECK(std::isfinite(time_offset));
   To<KeyframeEffect>(content_.Get())
       ->StartAnimationOnCompositor(compositor_group_, start_time,
                                    base::TimeDelta::FromSecondsD(time_offset),

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

@@ -97,7 +97,7 @@ class TestAnimationEffect : public AnimationEffect {
       bool forwards,
       base::Optional<double> local_time,
       AnimationTimeDelta time_to_next_iteration) const override {
-    DCHECK(!local_time || !Timing::IsNull(local_time.value()));
+    DCHECK(!local_time || std::isfinite(local_time.value()));
     local_time_ = local_time;
     time_to_next_iteration_ = time_to_next_iteration;
     return AnimationTimeDelta::FromSecondsD(

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

@@ -16,7 +16,7 @@ Keyframe::PropertySpecificKeyframe::PropertySpecificKeyframe(
     scoped_refptr<TimingFunction> easing,
     EffectModel::CompositeOperation composite)
     : offset_(offset), easing_(std::move(easing)), composite_(composite) {
-  DCHECK(!Timing::IsNull(offset));
+  DCHECK(std::isfinite(offset));
   if (!easing_)
     easing_ = LinearTimingFunction::Shared();
 }

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

@@ -82,7 +82,6 @@ struct CORE_EXPORT Timing {
   using FillMode = CompositorKeyframeModel::FillMode;
   using PlaybackDirection = CompositorKeyframeModel::Direction;
 
-  static bool IsNull(double value) { return std::isnan(value); }
   static double NullValue() { return std::numeric_limits<double>::quiet_NaN(); }
 
   static String FillModeString(FillMode);

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

@@ -61,14 +61,14 @@ inline bool LessThanOrEqualToWithinEpsilon(double a, double b) {
 }
 
 static inline double MultiplyZeroAlwaysGivesZero(double x, double y) {
-  DCHECK(!Timing::IsNull(x));
-  DCHECK(!Timing::IsNull(y));
+  DCHECK(!std::isnan(x));
+  DCHECK(!std::isnan(y));
   return x && y ? x * y : 0;
 }
 
 static inline double MultiplyZeroAlwaysGivesZero(AnimationTimeDelta x,
                                                  double y) {
-  DCHECK(!Timing::IsNull(y));
+  DCHECK(!std::isnan(y));
   return x.is_zero() || y == 0 ? 0 : (x * y).InSecondsF();
 }