stylo: Bug 1335998 - Handle interpolation and accumulation of mismatched transform lists
These are the interdependent patches of Bug 1335998. We want to do interpolation and accumulation for mismatched transform lists, so introduce ComputedOperation::InterpolateMatrix and ComputedOperation::Accumulation. Both arms store the from_list and to_list, and resolve them until we have the layout information. For the Servo part, we haven't implemented how to read the transform lists in layout/fragment.rs, but I think it would be easy. (related issue #13267)
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix [Bug 1335998](https://bugzilla.mozilla.org/show_bug.cgi?id=1335998)
- [X] There are tests for these changes
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We convert ComputedOperation::{Accumulate, Interpolate}Matrix into gecko type
not on the main thread, so we cannot use nsCSSValueList_heap (which is not
thread safe so we cannot create it and destroy it on different threads).
Therefore, we use nsCSSValueSharedList to represent the cloned
from_list/to_list. In this patch, we also implement the reversing way,
i.e. Convert eCSSKeyword_{accumulate, interpolate}matrix into
{Accumulate, Interpolate}Matrix.
If we set the composite operation to accumulate, we may need to accumulate two
mismatched transform lists, and then to interpolate them. In order to
accumulate two mismatched transform lists, we also need the reference
box information, so use the same idea as that for interpolation. i.e.
use AccmulateMatrix to store it temporarily, and convert it into matrix
later.
We use this arm to store the interpolated result of two mismatched
transform lists, and we resolve it until we know the reference box size
(on Gecko side). The conversion from ComputedOperation::InterpolateMatrix
to eCSSKeyword_interpolatematrix will be implemented later in this patch series.
To support visited styles, we match and cascade a separate set of styles any
time we notice that an element has a relevant link.
The visited rules and values are held in `ComputedStyle` alongside the
regular rules and values, which simplifies supporting various APIs like
`cascade_primary_and_pseudos` which expect easy access to previously matched
rules.
To simplify passing the additional values around, an additional reference to the
visited `ComputedValues` is placed inside the regular `ComputedValues`.
MozReview-Commit-ID: 2ebbjcfkfWf
Fix stylo's text-overflow handling to match gecko.
A single value sets the text-overflow on the _end_ of the text, not both start and end.
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