Test for #18544 - Flow list crash
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#18544
- [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/19834)
<!-- Reviewable:end -->
Do not leave space below baseline when it is not needed (i.e.there is…
… no text)
This is my first layout fix and a naive approach to fix#18831.
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#18831
<!-- 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/19789)
<!-- Reviewable:end -->
style: Move cursor property out of mako
<!-- Please describe your changes on the following line: -->
Sub-PR of #19015
r? emilio
---
<!-- 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 build-geckolib` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#19775 (github issue number if applicable).
<!-- Either: -->
- [x] These changes do not require tests
<!-- 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/19798)
<!-- Reviewable:end -->
It used to be the case that MatchingContext was immutable and thus we didn't
care to have accessors.
This is no longer true, so let's make this code a bit nicer.
Implement Element::has_css_layout_box()
r? emilio
Here's my initial attempt to fix#19430. It seems surprisingly simple so I am wondering whether I have missed something! (Or maybe it just actually is quite simple...)
Some things I am unsure about:
1. The spec seems vague about what a [CSS layout box](https://drafts.csswg.org/cssom-view/#css-layout-box) actually is. Indeed it says: "The terms CSS layout box and SVG layout box are not currently defined by CSS or SVG."
2. One thing the spec *does* say explicitly is "For the purpose of the requirements in this specification, elements that have a computed value of the display property that is table-column or table-column-group must be considered to have an associated CSS layout box (the column or column group, respectively)." I am unclear about the relevance of this, since [overflow does not apply](https://drafts.csswg.org/css-overflow-3/#overflow-properties) to an [internal table element](https://drafts.csswg.org/css-display-3/#layout-specific-display). Therefore I haven't done anything about this explicitly, but maybe I'm missing some nuance.
<!-- 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/19803)
<!-- Reviewable:end -->
Remove gecko-media dependency
The effort to import Gecko's media stack into Servo has been canceled, so I am removing the bits of code from gecko-media that we added to Servo.
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
<!-- 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/19806)
<!-- Reviewable:end -->
