Some janitoring over the layout crate
This PR moves a bunch of code around and makes some methods from one-use traits into inherent methods.
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/22684)
<!-- Reviewable:end -->
Implement Element::set_url_attribute
<!-- Please describe your changes on the following line: -->
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [ ] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#22568
<!-- Either: -->
- [ ] There are tests for these changes
<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/22682)
<!-- Reviewable:end -->
Fix ServoDriver is_alive method
<!-- Please describe your changes on the following line: -->
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#22664
<!-- Either: -->
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because it fixes test runner
<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/22673)
<!-- Reviewable:end -->
Implement Ended media attribute
<!-- Please describe your changes on the following line: -->
This PR should implement:
* New method `HTMLMediaElement::earliest_possible_position()` for the [earliest possible position](https://html.spec.whatwg.org/multipage/media.html#earliest-possible-position)
* `Ended` attribute following https://html.spec.whatwg.org/multipage/media.html#ended-playback
* Queue steps for when the playback position reaches the end
This PR contains placeholders for the following issues (I can rebase changes after the corresponding PRs get merged)
- #22321 (Define the Loop attribute)
- #22293 (To identify playback direction. Either forwards or backwards)
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [x] These changes fix#22294.
<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/22348)
<!-- Reviewable:end -->
Based on https://bugzilla.mozilla.org/show_bug.cgi?id=1348519#c6 and
https://github.com/w3c/csswg-drafts/issues/3201:
Currently grid-template-rows/columns interpolate “per computed value”, which
means that if the number of tracks differs, or any track changes to/from a
particular keyword value to any other value, or if a line name is added/removed
at any position, the entire track listing is interpolated as “discrete”.
But we "agree" with two more granular options:
1. Check interpolation type per track, rather than for the entire list, before
falling back to discrete. I.e. a length-percentage track can animate between
two values while an adjacent auto track flips discretely to min-content.
2. Allow discrete interpolation of line name changes independently of track
sizes.
Besides, for the repeat() function, it's complicated to support interpolation
between different repeat types (i.e. auto-fill, auto-fit) and different repeat
counts, so we always fall-back to discrete if the first parameter of repeat()
is different.
Differential Revision: https://phabricator.services.mozilla.com/D16129
Implement DOM APIs for ChannelSplitterNode
<!-- Please describe your changes on the following line: -->
Based on #21591. Fixes#21558. I tried to update the expected results for WPT using "./mach update-wpt"; let me know if I got something wrong.
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix the second half of #21558
<!-- Either: -->
- [x] There are web-platform-tests tests for these changes
- [ ] These changes do not require tests because ___
<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/22648)
<!-- Reviewable:end -->
Remove trailing ? when updating URLSearchParams
---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#22639
- [x] There are tests for these changes
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/22666)
<!-- Reviewable:end -->
