Stop using / as division

[nex3]

• Deprecation, divide(), and slash-list()
• Removal of /-as-division, deprecation of slash-list() ([Slash Separator] Parse / as a separator rather than a division operator #2649)
• Removal of slash-list()

See sass/sass#2565

[tysonmatanich]

Is there a perf or other difference between using calc(9 / 16) vs math.div(9, 16)? I read through the docs and couldn't figure out the reason for using one over the other. Thanks!

[jathak]

For division on literals, both should be equivalent (there should be minimal, if any, performance differences), but in more complicated cases, Sass may not be able to fully simplify a calc at compile time (e.g. 40px + 10%), so it will be emitted in the final CSS, whereas math.div will always either return a number or produce an error.