Please upgrade source-map to 0.7.2 to get speed improvements

[andreicristianpetcu]

The latest source-map which is v0.7.2 got support for WebAssembly and it is 10 times faster than the old one. More info here:

https://github.com/mozilla/source-map/blob/master/CHANGELOG.md#072
http://fitzgeraldnick.com/2018/02/26/speed-without-wizardry.html
https://hacks.mozilla.org/2018/01/oxidizing-source-maps-with-rust-and-webassembly/
firefox-devtools/debugger#5598

Please update so you would get 10 times speed improvements for your library in Firefox, 9 times in Safari and 5 times in Chrome.

[jakubpawlowicz]

Sure, we can do it in 4.2.0.

[realityking]

Note source-map 0.7 requires Node.js 8

[jakubpawlowicz]

I planned to drop Node.js 4 in clean-css 5 but there may be a point in dropping Node.js 6 too when Node.js 10 is out so we can use the source-map 0.7.

[jakubpawlowicz]

Won't fix. I've tried to migrate to source-map 0.7 multiple times and their promise-based API didn't work for me. Closing it as clean-css is going into maintenance mode.