Merge pull request #772 from kangax/clean-css-4
authorAlex Lam S.L <alexlamsl@gmail.com>
Tue, 24 Jan 2017 16:53:32 +0000 (00:53 +0800)
committerGitHub <noreply@github.com>
Tue, 24 Jan 2017 16:53:32 +0000 (00:53 +0800)
upgrade to clean-css 4.0


Trivial merge