Blockify elements in a flex container
<!-- Please describe your changes on the following line: -->
The is one of my pull requests that implement basic flexible box layout.
As the spec stated in https://drafts.csswg.org/css-flexbox/#flex-items ,
A inline-level child of a flex container should be converted to its block equivalent, according to CSS2.1 § 9.7.
---
<!-- 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
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because flexbox is not actually implemented yet.
<!-- 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/12361)
<!-- Reviewable:end -->
layout: Clear non-inherited properties on anonymous block
<!-- Please describe your changes on the following line: -->
This is one of my pull requests that imlement basic flexible box layout.
This pull request adds a `modify_style_for_anonymous_flow()` function to use initial values for non-inherited properties and parent values for inherited properties as the flow style. It also set border and outline to zero and set the display property from the parameter. This function may also be reused to modify style of anonymous table object in the future.
Part of code comes from `cascade_anonymous()` from @SimonSapin .
---
<!-- 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
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because flexbox is not implemented yet.
<!-- 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/12382)
<!-- Reviewable:end -->
Add a modify_style_for_anonymous_flow() function to use initial values
for non-inherited properties and parent values for inherited properties
as the block style. It also set border and outline to zero and set the
display property from the parameter.
Rotate animation
Add rotation interpolation code for the case where their direction vectors are equal.
___
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#11808 (github issue number if applicable).
- [X] There are tests for these changes
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11873)
<!-- Reviewable:end -->
It seems python in msys2 has some weird behavior. For __file__, it
returns a string which uses windows-style separator '\', however,
os.path.dirname only recognizes the unix-style separator '/', and
consequently, the path of Mako is not added properly.
The previous behavior is plain wrong, since that array has always at least one
element, so we effectively couldn't specify anything else than "ease" in our
animations.
Support 'flex' and 'flex-flow' shorthand properties
<!-- Please describe your changes on the following line: -->
Support the `flex` and `flex-flow` shorthand properties in
servo. Currently they are marked as experimental, so they are added to
`__dir__.ini`.
Thanks SimonSapin and jdm for help :)
---
<!-- 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] There are tests for these changes
<!-- 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="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11948)
<!-- Reviewable:end -->