Intent to ship: animation-composition property

[Boris Chiou]

As of Firefox 115, I intend to turn "animation-composition" on by default on all platforms. It has been developed behind the "layout.css.animation-composition.enabled" preference. There is no new issue about it and the spec is a First Public Working Draft.

Status in other browsers is:

1. Google Chrome: shipped in Feb. (https://groups.google.com/a/chromium.org/g/blink-dev/c/5Lg0kHOUZ8Y/)
2. WebKit: shipped

Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=1823862

Standard: https://www.w3.org/TR/css-animations-2/#animation-composition

This feature was previously discussed in this "Intent to prototype" thread: https://groups.google.com/a/mozilla.org/g/dev-platform/c/s0_mISL9ac8/m/T30J9lfOAgAJ

Thanks,

Boris