Replace division with multiplication

[senchden]

Addresses #2668. Removed slash character to be compatible with the newer versions of sass compiler. Tested and does not brake compatibility since resulting CSS is not changed.

[NicolasCARPi]

Thanks, indeed this should not cause any issues. But the sass doc recommends using math.div. I think it is better to use math.div as it might handle better different values of $amnt (compared to the * operator). But this is pure supposition, maybe the check if > 1 above is enough to make sure no weird values are there. Anyway, I would still side with the documented change.

[senchden]

Yes, it could be replaced with math.div. But I have done it this way if to keep backwards compatibility with libsass/node-sass (just like in bootstrap). In fact, multiplication is what official sass migrator came up with. If you don't need it, I can replace it with math.div

[NicolasCARPi]

For me you provided a valid reason to use the multiplication so let's use that then! Thanks!

[NicolasCARPi]

dammit, I fat fingered the commit message.... oh well....