Update wgpu and WebGPU CTS to include copy validation tests
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r?@kvark
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Implement GPUUncapturedErrorEvent
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A new `uncapturederror` variant is added to atoms/static-atoms.txt. `GPUUncapturedErrorEvent` is fired when an error is not captured by any `ErrorScope`.
All tests for error scopes `PASS` now.
r?@kvark
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Do not load srcdoc iframes synchronously
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- [x] These changes fix#24718
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Update WebGPU CTS to main branch
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`main` branch in https://github.com/gpuweb/cts is closer to our implementation and it makes more sense to use that.
r?@kvark
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