If we're restyling a page with animations and layout takes too long, we
might still have the expired animations from the last restyle, without these
being cleared out by layout on `tick_animations`.
Unfortunately it's hard (near to impossible?) to make a reduced test case for
this, since it heavily depends on the speed of the build and conditions that
only happen under heavy loads.
Mainly, it depends on how accurately the `TickAllAnimations` message is sent
from the constellation.
Thus, we can't just re-expire an animation, and we should re-check for it as a
previous animation.
Fixes#12171
As a follow-up, we could move all the data living under a mutex in the
SharedLayoutContext only in order to create the local context to the same place.
This should increase animation performance when there are multiple animations in
one page that happen to be on different threads.
There's a bit of flickering when unpausing where the node has the original
state, but I'm not totally sure where it comes from, posibly from
PropertyAnimation returning None due to no styles changing?
So this actually allows some more animations to be triggered. The bad part of
this is that they're actually triggered always when the style is recalculated,
so we're going to have at least some more state into the node, and the
constellation, which would have to keep track of the animations states.
These can't be supported in Servo as of right now, because I'm not
totally sure the accesses that should be done in layout would be
thread-safe.
It can be revisited later though.
This commit refactors the style crate to be completely independent of
the actual implementation and pseudo-elements supported.
This also adds a gecko backend which introduces parsing for the
anonymous box pseudo-elements[1], although there's still no way of
querying them.
https://mxr.mozilla.org/mozilla-central/source/layout/style/nsCSSAnonBoxList.h
We do a few things-here:
* Hoist non-layout-dependent fields in SharedLayoutData and LocalLayoutData into style/.
* Hoist parts of css/matching.rs into style/.
* Hoist parts of layout/animation.rs into style/animation.rs.
* Remove the duplicated-but-slightly-different definition of OpaqueNode.
