Bump node-sass from 4.9.3 to 4.9.4 in /js

Bumps [node-sass](https://github.com/sass/node-sass) from 4.9.3 to 4.9.4.
- [Release notes](https://github.com/sass/node-sass/releases)
- [Changelog](https://github.com/sass/node-sass/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sass/node-sass/compare/v4.9.3...v4.9.4)

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

js/package.json

@@ -29,7 +29,7 @@
     "css-loader": "^1.0.0",
     "karma": "^3.0.0",
     "mini-css-extract-plugin": "^0.4.4",
-    "node-sass": "^4.9.3",
+    "node-sass": "^4.9.4",
     "webpack": "^4.22.0",
     "webpack-cli": "^3.1.2",
     "webpack-merge": "^4.1.4"