<!-- Please describe your changes on the following line: -->
This is the final PR to get basic paint worklet support. It adds support for paint worklet properties (https://drafts.css-houdini.org/css-paint-api/#paint-definition-input-properties). When a paint worklet is registered, it specifies a list of CSS properties, and is provided with their computed values when it is invoked.
This is a dependent PR:
* "Implemented paint worklets invoking worklet scripts" is #17239.
* "Implemented paint worklets rendering contexts" is #17326.
There should be tests added for this, hopefully the existing wpt houdini tests.
---
<!-- 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#16839
- [x] 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. -->
Source-Repo: https://github.com/servo/servo
Source-Revision: bc44246fc682d9f2362eaca6bba07b45c293eb42
<!-- Please describe your changes on the following line: -->
This PR implements the current draft Houdini Worklets specification (https://drafts.css-houdini.org/worklets/).
The implementation is intended to provide a responsive environment for worklet execution, and in particular to ensure that the primary worklet executor does not garbage collect, and does not block loading module code. The implementation does this by providing a thread pool, and performing GC and module loading in a backup thread, not in the primary thread.
---
<!-- 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#16206
- [x] 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. -->
Source-Repo: https://github.com/servo/servo
Source-Revision: ac99a48aeaa184d3acdb39d249636a140c4b7393
