Add a copy of WebGPU CTS to wpt.
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The test suite is generated from `glsl-dependent` branch in https://github.com/gpuweb/cts
We already have 6/44 tests passing and a number of subtests in other tests also pass.
r?@jdm
cc @kvark
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Upgrade flake8/pyflakes for Py3 compatibility
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Do not raise StopIteration: PEP 479
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This fixes `test-tidy` Py3 compatibility, as [PEP 479](https://www.python.org/dev/peps/pep-0479/) says `return` must be used to stop iteration inside generator instead of `raise StopIteration`.
This introduces subtle behavior change where `FileList()` constructor now won't implicitly stop the caller generator when the list is empty. `wpt_lint.py` is modified to explicitly stop when empty, to match the change.
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Initial implementation of WebGPU API
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- Added the WebIDL bindings for GPU and GPUadapter interfaces.
- Created a background thread for WebGPU api calls.
- Established the async communication between the background thread and the WebGPU interfaces.
- Implemented the `requesAdapter` function of `navigator.gpu`
`./mach test-tidy` reports an error due to the different `arrayvec` version used in `servo` and `webgpu`, so added it to the ignore list in `servo-tidy.toml`
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- [ ] These changes addresses a part of #https://github.com/servo/servo/issues/24706
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cc @jdm, cc @kvark
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Include missing dependency requirements
Running `servo-tidy` in a virtualenv where all you've done is `pip install servo-tidy==0.3.0` doesn't actually work because of missing dependencies. PyYAML and voluptuous are required as well. I don't know anything about python package management but declaring these missing dependencies seems like an appropriate thing to do. Patch itself is untested because I don't know how, although with these dependencies installed in my virtualenv running `servo-tidy` works.
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Running `servo-tidy` in a virtualenv where all you've done is `pip install servo-tidy==0.3.0` doesn't actually work because of missing dependencies. PyYAML and voluptuous are required as well. I don't know anything about python package management but declaring these missing dependencies seems like an appropriate thing to do. Patch itself is untested because I don't know how, although with these dependencies installed in my virtualenv running `servo-tidy` works.
