Bump webpack from 4.16.3 to 4.16.4 in /js

Bumps [webpack](https://github.com/webpack/webpack) from 4.16.3 to 4.16.4.
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](https://github.com/webpack/webpack/compare/v4.16.3...v4.16.4)

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

js/package.json

@@ -28,7 +28,7 @@
     "karma": "^2.0.5",
     "mini-css-extract-plugin": "^0.4.1",
     "node-sass": "^4.9.2",
-    "webpack": "^4.16.3",
+    "webpack": "^4.16.4",
     "webpack-cli": "^3.1.0",
     "webpack-merge": "^4.1.3"
   },