./mach test-tidy should also check .html files, to avoid patches containing badly formatted new test cases go unnoticed
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#12421
- [X] There are tests for these changes (./mach test-tidy failed without the changes to .hrml files)
Source-Repo: https://github.com/servo/servo
Source-Revision: 93004ce57999947f51067d680c6fde056741331a