Bump mocha from 5.2.0 to 6.1.4

Bumps [mocha](https://github.com/mochajs/mocha) from 5.2.0 to 6.1.4.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v5.2.0...v6.1.4)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Author: dependabot-support

package.json

@@ -29,7 +29,7 @@
     "benchmark": "^2.1.0",
     "browserify": "^16.2.3",
     "klass": "^1.4.0",
-    "mocha": "^5.0.0",
+    "mocha": "^6.1.4",
     "traceur-runtime": "0.0.59",
     "uberproto": "^2.0.0"
   },