build(mach): locate vs via vswhere on win32
<!-- Please describe your changes on the following line: -->
This PR tries to improve Visual Studio installation lookup in mach.
It includes changes
- lookup VS2017 installation via `vswhere` (https://github.com/Microsoft/vswhere) allows non-default location installation eventually.
: currently PR does uses vswhere binary from VS installation itself, but vswhere binary can be placed separately without VS (github repo publishes binary releases also) - allows VS lookup without any dependency to binary / path / or env variables. For VS15, it falls back to same logic based on file path as vswhere supports from VS17 and above.
- assign environment variable in python process
: This is mostly for some non-default win32 environment who doesn't uses cmd.exe as default shell (myself). For example, if default shell is zsh, running vcvarsall.bat doesn't inherit env variable into current shell. Instead, this PR borrows implementation of Electron (https://github.com/electron/electron/blob/master/script/lib/env_util.py) which established inheriting env variable into python process itself, doesn't care about primary shell invoked scripts.
Still `mach.bat` remains for compatibility purpose, but `mach` take cares of all of jobs.
---
<!-- 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
- [ ] `./mach build-geckolib` does not report any errors
- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____
- Locally built & run on windows machine
<!-- 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/20543)
<!-- Reviewable:end -->
style: Move `clear` CSS property outside mako
This is part of issue #19015.
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#21155
<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] 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/21156)
<!-- Reviewable:end -->
Introduce "per task source" cancellation
<!-- 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
- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix#21119 (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] 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/21126)
<!-- Reviewable:end -->
style: Move `float` CSS property outside mako
Hi, I am fairly new to Rust and this is my first contribution to a Rust project.
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#21130
<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____
I'm not sure if the approach with the two enums is good. Please let me know if this can be improved.
Regarding the tests I'm unsure: `tests/wpt/web-platform-tests/css/css-display/display-contents-float-001.html` seems to fail already before this PR, (and the cause is maybe not related to the style property definition).
Also I would like to add some docs, is it allowed to use the descriptions from MDN (https://developer.mozilla.org/en-US/docs/Web/CSS/float).
<!-- 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/21139)
<!-- Reviewable:end -->
Exposing HTMLSourceElement IDL attributes
<!-- 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
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [x] There are tests for these changes OR
- [ ] 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/21120)
<!-- Reviewable:end -->
Make (dictionary)::empty() safe
It currently works by constructing from null (which will throw a runtime
error if there are non-defaultable members).
This changes it so that we no longer need a JSContext to construct this,
so it can be safely constructed. In the case of non-defaultable members,
this method simply does not exist.
<!-- 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/21131)
<!-- Reviewable:end -->
It currently works by constructing from null (which will throw a runtime
error if there are non-defaultable members).
This changes it so that we no longer need a JSContext to construct this,
so it can be safely constructed. In the case of non-defaultable members,
this method simply does not exist.
Store vertex attribs data in DOM and optimise GetVertexAttrib
This is not an extremely useful change on its own but those things need to be stored on the DOM side to implement some draw checks anyway.
<!-- 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/21118)
<!-- Reviewable:end -->
