Test in other browsers/environments?

[armanbilge]

Notably:

• Safari seems much more popular than Firefox. Selenium supports Safari, just needs some GH actions tinkering to get these to run on MacOS. To support the webworker tests as well will require finding the equivalent of profile.setPreference("privacy.file_unique_origin", false) or options.addArguments("--allow-file-access-from-files").

[djspiewak]

I think this would be worth doing! The main reason I didn't is the fact that Chrome, Safari, and Firefox all behave similarly with respect to the polyfill. The more the merrier though, particularly now that we're decoupled from CE.