[conradk]

It looks like Mozilla is testing for virtually any web browser that is in use. That seems OK.

And, you can choose to do feature detection if you wish. Here's a quick example:

https://cdn.polyfill.io/v1/polyfill.js?features=Array.protot...

More information about that can be found here: https://cdn.polyfill.io/v1/docs/api