As well as being required to implement absolutization this also means we
now bypass a limitation with `LengthPercentage` where we would always
use `SerializationMode::Normal` for the constituent lengths which gains
us some WPT passes
Some subtests changed in response to this CSSWG resolution:
https://github.com/w3c/csswg-drafts/issues/11494#issuecomment-2675800489
Basically, `border-style: none` now affects the used value of
`border-width`, not the computed value. (And the same for `outline`
properties.)
This affects way more tests than I expected because
interpolation-testcommon.js now adds tests for composition.
This also allows us to remove the path generation and interpolation
handling for `rect()` and `xywh()` since that occurs after computation
Regressions in clip-path-interpolation-xywh.html are due to improper
simplification of length-percentage mixes where the length is 0px.
Fixes a crash on https://www.lego.com/en-gb/product/game-boy-72046 :^)
The apparent regressions in clip-path-interpolation-xywh-rect.html are
because of false positives. Something about the test was causing it to
compare two wrong values that happened to be the same. Now one of the
values is correct, they don't match.
