Use the polyfill version of u2f API provided by Google.
https://github.com/mastahyeti/u2f-api
This polyfill is at least compatible with Chrome and
Firefox after enabling the U2F support.
[HOWTO] Enable U2F in Firefox >= 57:
Navigate to 'about:config' and search for 'u2f' option.
Double-click on the line to toggle the option.
