[Button] Problem with icon in fluid button under Firefox

[mzygmunt]

Problem: Problem with icon in fluid button under Firefox (only Firefox).
JSFiddle: https://jsfiddle.net/rduvhn8u/67/
Screen:
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:39.0) Gecko/20100101 Firefox/39.0

[jlukic]

See flegbugs issue #9

I probably should swap fluid buttons from using flex since many people use this pattern.

[jlukic]

Removed flex from fluid