Negative animation playbackRate

[mkeblx]

Negative animation playback rates can be useful. Should we specify that model element supports a negative playbackRate?

There is some related discussion (linked below) w.r.t. video supporting a negative playbackRate and the challenges with that, however model doesn't have the same technical issues as video.

Some references:

• https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/playbackRate
• https://github.com/whatwg/html/issues/2754
• https://bugzilla.mozilla.org/show_bug.cgi?id=1468019

[zachernuk]

Good call! I think we don't have it in 2.4, but

1. It's because of stuff underneath us and
2. I don't think there's a principled or immovable reason why we'd want to keep this requirement forever.
   /agenda