While I can't reproduce the issue on Chrome/Win10 or Firefox/Win10 in my testing adding a directly after the icon doesn't change much for me locally either but I expect the Android Webview might not collapse white-space when it is a non-breaking-white-space one. That would fix the issue on your device / setup.
This pull-request had the proposed change.
But when Nick kindly tested that change it turned out to not solve the issue. It needed extra CSS for that work on Mobile Chrome:
[class^="icon-"] {
margin-right: .3em;
}css
but that lead to a much wider space on all other browsers.
I'm not ready yet to support minor glitches with per browser tweaks. Until someone else has a better solution this stays status-bydesign, sorry.
Do not allow for 6 to 8 weeks to have the PR merged and deployed.