closurecompiler: 20180204 -> 20180319

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/closure-compiler/versions.

These checks were done:

- built on NixOS
- ran `/nix/store/5cwv2kws2j74bchi3gd1fknaxglrplmi-closure-compiler-20180319/bin/closure-compiler --help` got 0 exit code
- ran `/nix/store/5cwv2kws2j74bchi3gd1fknaxglrplmi-closure-compiler-20180319/bin/closure-compiler --version` and found version 20180319
- found 20180319 with grep in /nix/store/5cwv2kws2j74bchi3gd1fknaxglrplmi-closure-compiler-20180319
- found 20180319 in filename of file in /nix/store/5cwv2kws2j74bchi3gd1fknaxglrplmi-closure-compiler-20180319
- directory tree listing: https://gist.github.com/f4c40a73ba5b7b3b9eeb7c65db12a641