The following test currently times out:

external/wpt/web-animations/timing-model/animations/updating-the-finished-state.html
  - Finish notification steps run when the animation completes with .finish() even if we then seek away

I have not yet root-caused the reason, but it appears that we do not fire an onfinish event in this test once finish() is called:

[1:1:1005/133447.157750:10892766873719:INFO:Animation.cpp(646)] Animation::finish() called
[1:1:1005/133447.157909:10892766873812:INFO:Animation.cpp(1151)] ResolvePromiseMaybeAsync for finished_promise_
[1:1:1005/133447.158902:10892766874871:INFO:Animation.cpp(941)] Animation::Update: idle ? 0, Limited() ? 0, finished_ ? 0

The final log above is from Animation::Update, which is responsible for generating the onfinish event (as well as setting finished_):

bool Animation::Update(TimingUpdateReason reason) {
...
  if ((idle || Limited()) && !finished_) {
...
          timeline_->GetDocument()->EnqueueAnimationFrameEvent(
              pending_finished_event_);
...
}

In the code, idle, Limited(), and finished_ are all false so the 'if' statement is never entered. I'm not yet clear what the correct solution is here - not sure what Limited() is about.