Intent to ship: Web Animations Animation timelines (without the setter of Animation.timeline)

[Boris Chiou]

Hi,

We intend to turn on the preference of the Animation timelines this week.
* dom.animations-api.timelines.enabled

This preference enables Animation.timeline getter, Document.timeline, and
DocumentTimeline and AnimationTimeline interfaces.

This feature has been implemented in WebKit and Blink in their nightly
version, but
they haven't shipped this to their release channels yet. We expect this
will happen
soon in the next version of Safari and shortly after in Chrome.

We implemented and enabled this (together with mutable Animation.timeline)
at least
3 years ago, and recently we added a build flag to enable mutable
Animation.timeline
only on Nightly version, so we can easily ship read-only Animation.timeline
and others
by the pref. WebKit and Blink are ready to ship this feature recently, so
we would like
to ship it too in Firefox 75.

Bug to turn this on by default:
https://bugzilla.mozilla.org/show_bug.cgi?id=1619178

There is no specific intent to prototype these features. They have been
implemented as part of the ongoing work on the Web Animations API.

There are various web-platform-tests which use the getter of
Animation.timeline,
Document.timeline in
web-an
<https://searchfox.org/mozilla-central/source/testing/web-platform/tests/web-animations/timing-model/timelines>
imations/timing-model/timelines
<https://searchfox.org/mozilla-central/source/testing/web-platform/tests/web-animations/timing-model/timelines>
and a lot of places in web-an
<https://searchfox.org/mozilla-central/source/testing/web-platform/tests/web-animations/interfaces>
imations/interfaces/
<https://searchfox.org/mozilla-central/source/testing/web-platform/tests/web-animations/interfaces>
.
And there are some web-platform-tests for
AnimationTImeline/DocumentTimeline in
web-animations/interfaces/DocumentTimeline.
<https://searchfox.org/mozilla-central/source/testing/web-platform/tests/web-animations/interfaces/DocumentTimeline>

Please let me know if you have any concerns.

Best regards,
Boris