[PSA] Web Platform Tests that require MojoJS now work on wpt.fyi

[Robert Ma]

Hello Blink developers,

I'm happy to announce that Web Platform Tests (WPT) that require MojoJS now work upstream (on wpt.fyi) with official binaries out of the box starting from M86 (currently Dev). Check out WebXR and WebUSB test results before and after enabling MojoJS. (These tests continue to work in Chromium CI.)

Most of the generated *.mojom.js files checked into web_tests/external/wpt have been removed (the remaining will be soon). There is no need to check generated Mojo bindings into WPT from now on; a presubmit check has been added.

You can find more about how to add new MojoJS-backed tests in this doc. Note that testdriver.js (WebDriver extensions) still remain our top recommendation for test automation. Feel free to reach out to ecosyst...@chromium.org if you have any questions.

Cheers,

Robert from Ecosystem Infra team