Queue the long animation frame entry when presentation is ready

[noamr]

Together with w3c/long-animation-frames#22

When presentation timing is ready, we queue the entry with the paint timing info.

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[mmocny]

As discussed in person: I think that this solution means that Paint Timing will have to have explicit references to every specific entry type that requires paint timing. An alternative would have been to use a common hook/callback to request and receive just the timings. But I know you thought this was a good choice and did it by design.

[noamr]

As discussed in person: I think that this solution means that Paint Timing will have to have explicit references to every specific entry type that requires paint timing. An alternative would have been to use a common hook/callback to request and receive just the timings. But I know you thought this was a good choice and did it by design.

Yes! I think hooks are brittle and make the order unclear and bug-prone. They're not necessary when we have a constant set of APIs that need this.

For reference, the HTML spec does not use hooks/observers as it was causing this kind of issue. See for example https://html.spec.whatwg.org/multipage/interaction.html#update-the-visibility-state.