Add support for getComputedStyle() to layout_2020
These changes add support for `getComputedStyle()` to layout_2020.
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This implementation is more-or-less on par with the one from layout_2013
and in some cases better. There are still some cases where we don't
return the correct "resolved value," but this is enough to test
animations and transitions.
This change corrects synchronization issues with animations, by
reworking the animation processing model to do a quick restyle and
incremental layout when ticking animations.
While this change adds overhead to animation ticks, the idea is that
this will be the fallback when synchronous behavior is required to
fulfill specification requirements. In the optimistic case, many
animations could be updated and applied off-the-main-thread and then
resynchronized when style information is queried by script.
Fixes#13865.
Refactor ImageCache::find_image_or_metadata -> ImageCache::{get_image, track_image}
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Updated the `ImageCache` trait to replace `find_image_or_metadata` with two new functions `track_image` and `get_image`, as well as a new enum (`ImageCacheResult`).
As a result, I was able to refactor the functions that previously called `find_image_or_metadata` pretty cleanly. For a list of these functions, please see the commit information.
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- [x] These changes do not require tests because tests already exist for these components. I ran `cargo test` in `net`, `net_traits`, `layout`, and `script` successfully.
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Ensure reference frame is popped in layout 2020
closes: #26066
Should be equivalent to https://github.com/servo/servo/pull/26063 for layout2020
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layout_2020: Stop throwing away hoisted boxes in nested absolutes
We were previously throwing away some boxes hoisted to containing blocks
for all descendants when they were contained by absolutes. This prevents
panics in existing web platform tests that would otherwise be triggered
by the addition of the `unreachable!` statement.
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We were previously throwing away some boxes hoisted to containing blocks
for all descendants when they were contained by absolutes. This prevents
panics in existing web platform tests that would otherwise be triggered
by the addition of the `unreachable!` statement.
This avoids the use of lookup tables for containing blocks when
constructing the stacking context tree.
This seems to catch some laid-out hoisted fragments that were otherwise
dropped in the previous design. The changes cause one new test to pass
and one to fail. Visual examination of the failing tests reveals that
it's a progression (list markers are appearing when they were previously
not rendered).
layout_2020: Use ArcRefCell in the fragment tree
This will allow mutability which is useful for things like animations.
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