Auto spacing in Firefox search bar does not work As the title says, the auto spacing feature does not work in Firefox search bar. 
This issue seems to be related only with that bar, because auto spacing works fine
in forms or text fields in web pages and it works in the other apps too. 
My Android version: 4.4.2
I hope somebody else has already experienced this problem.
This is a known bug.  It seems like it was introduced with 4.2.2.  Downgrading to before that is not a good option, but might be available to you.

It affects multiple browsers with multiple keyboards, so I assume the issue must be with the specific type of text field used for their address bars.  I used to encounter this with Chrome but haven't lately, so you could also try that browser instead of Firefox.  In the thread above, someone also mentioned that the stock Google keyboard did not cause the issue for them.