<!-- Please describe your changes on the following line: --> wpt manifest(include.ini) contains directories as headers. With this test in **test-tidy** we check if they are present in respective wtp test folders. --- - [X] `./mach build -d` does not report any errors - [x] `./mach test-tidy` does not report any errors - [X] These changes fix #19703 Source-Repo: https://github.com/servo/servo Source-Revision: f84e9236aee15348dc9bb3555500117fef922e12