https://github.com/web-platform-tests/wpt/pull/50041 allows us to start
running the webdriver conformance tests in Servo, which will make it
easier for us to track regressions/improvements in our webdriver server
implementation.
---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes are part of #15274
- [x] There are tests for these changes
---------
Signed-off-by: Josh Matthews <josh@joshmatthews.net>