Remove PlayStateUpdateScope from Animation::PostCommit.

Animation::PostCommit does not alter the state of any flags that affect
play state.

Bug: 960944
Change-Id: I3aff88c688aed376c046f249fd627187757ac280
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1911387Reviewed-by: Majid Valipour <majidvp@chromium.org>
Commit-Queue: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714932}

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

@@ -521,9 +521,6 @@ bool Animation::PreCommit(
 }
 
 void Animation::PostCommit(double timeline_time) {
-  PlayStateUpdateScope update_scope(*this, kTimingUpdateOnDemand,
-                                    kDoNotSetCompositorPending);
-
   compositor_pending_ = false;
 
   if (!compositor_state_ || compositor_state_->pending_action == kNone)