Bump [email protected]

See https://github.com/sass/libsass/releases/tag/3.5.4

Revert to [email protected] because of specs that depend on features
reverted in 3.5.4.

4.8.3

4.8.2

4.8.1

4.8.0

4.7.2

4.7.1

4.7.0

4.6.1

## Fixes

- Problem with watcher (@evanfuture, sass#2147)

## Supported Environments

| OS | Architecture | Node |
| --- | --- | --- |
| Windows | x86 & x64 | 0.10, 0.12, 1, 2, 3, 4, 5, 6, 7, 8, 9 |
| OSX | x64 | 0.10, 0.12, 1, 2, 3, 4, 5, 6, 7, 8, 9 |
| Linux* | x86 & x64 | 0.10, 0.12, 1, 2, 3, 4, 5, 6, 7, 8, 9 |
| Alpine | x64 | 4, 6, 7, 8, 9 |
| FreeBSD  10+ | i386 | 4, 6, 8 |
| FreeBSD 10+ | amd64 | 4, 6, 8 |

*Linux support refers to Ubuntu, Debian, and CentOS 5

4.6.0