[Fizz] If we haven't painted yet, wait to reveal everything until next paint #34230
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…t paint (#34230) Before the first rAF, we don't know if there has been other paints before this and if so when. (We could get from performance observer.) We can assume that it's not earlier than 0 so we used delay up until the throttle time starting from zero but if the first paint is about to happen that can be very soon after. Instead, this reveals it during the next paint which should let us be able to get into the first paint. If we can trust `rel="expect"` to have done its thing we should schedule our raf before first paint but ofc browsers can cheat and paint earlier if they want to. If we're wrong, this is at least more batched than doing it synchronously. However it will mean that things might get more flashy than it should be if it would've been throttled. An alternative would be to always throttle first reveal. DiffTrain build for [0bdb920](0bdb920)
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Before the first rAF, we don't know if there has been other paints before this and if so when. (We could get from performance observer.) We can assume that it's not earlier than 0 so we used delay up until the throttle time starting from zero but if the first paint is about to happen that can be very soon after.
Instead, this reveals it during the next paint which should let us be able to get into the first paint. If we can trust
rel="expect"to have done its thing we should schedule our raf before first paint but ofc browsers can cheat and paint earlier if they want to.If we're wrong, this is at least more batched than doing it synchronously. However it will mean that things might get more flashy than it should be if it would've been throttled. An alternative would be to always throttle first reveal.