I'm pretty sure that there is some such mechanism. At least, I've seen patches related to such a mechanism. I don't remember the specifics and I can't find the

I'm pretty sure that there is some such mechanism. At least, I've seen patches related to such a mechanism. I don't remember the specifics and I can't find the documentation right now, but I seem to remember that there was something called the "WebExtensions Extension API" or something such that let developers access existing unstable APIs. It's probably somewhere. Note that in this case, we're not discussing (only) "unsafe" APIs but also "unstable" APIs that can change from one day to the next without warning.