[Bug] AnimationControls.finished promise stays pending if it's not immediately used

[piotrjoniec]

1. Describe the bug

The AnimationControls.finished promise stays pending if it's not immediately used after creating the animation. If I await this promise after the animation has already finished, it will await forever, which is unlike the normal behavior of the "finished" promise in WAAPI.

2. IMPORTANT: Provide a CodeSandbox reproduction of the bug

https://codesandbox.io/p/devbox/motionone-bug-k37tnt?file=%2Fsrc%2Findex.mjs

3. Steps to reproduce

1. Open the CodeSandbox link.
2. Open the console.

4. Expected behavior

Console should show all "Case 1 finished", "Case 2 finished" and "Case 3 finished".

[piotrjoniec]

Here's another strange behavior:

When animating for the first time, the animation will end with playState of idle and currentTime will revert to 0.

But when animating for the second time by calling play() directly, the animation will end with playState of finished and currentTime of 1.