Intent to ship: Web Animations Animation.timeline setter

[Boris Chiou]

Hi,

We intend to enable the setter of Animation.timeline API for Firefox 102. We shipped the read-only Animation.timeline API already, based on https://groups.google.com/g/mozilla.dev.platform/c/pm3qlPUdO4o/m/sMlBa13ZGgAJ. And now we would like to enable the setter of Animation.timeline as well.

Other browsers:

1. Chrome shipped this already: https://groups.google.com/a/chromium.org/g/blink-dev/c/Wu4yPMznUw0/m/-LrirfTJBAAJ

2. Safari just enabled it in March: https://trac.webkit.org/changeset/291868/webkit/.

Bug to turn this on by default:

https://bugzilla.mozilla.org/show_bug.cgi?id=1767357

The tests are already in the wpt folders, e.g. web-animations, css-animations, and css-transitions, already, so all we need to do is to just remove the Nightly build flag from our codebase.

Please let me know if you have any questions.

Best regards,

Boris