build(deps): bump react-dom in /ihaskell_labextension

Bumps [react-dom](https://github.com/facebook/react/tree/HEAD/packages/react-dom) from 16.2.0 to 16.4.2.
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/master/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/v16.4.2/packages/react-dom)
Signed-off-by: dependabot[bot] <support@github.com>

ihaskell_labextension/package-lock.json

@@ -3318,9 +3318,9 @@
       }
     },
     "react-dom": {
-      "version": "16.4.1",
-      "resolved": "https://registry.npmjs.org/react-dom/-/react-dom-16.4.1.tgz",
-      "integrity": "sha512-1Gin+wghF/7gl4Cqcvr1DxFX2Osz7ugxSwl6gBqCMpdrxHjIFUS7GYxrFftZ9Ln44FHw0JxCFD9YtZsrbR5/4A==",
+      "version": "16.4.2",
+      "resolved": "https://registry.npmjs.org/react-dom/-/react-dom-16.4.2.tgz",
+      "integrity": "sha512-Usl73nQqzvmJN+89r97zmeUpQDKDlh58eX6Hbs/ERdDHzeBzWy+ENk7fsGQ+5KxArV1iOFPT46/VneklK9zoWw==",
       "requires": {
         "fbjs": "^0.8.16",
         "loose-envify": "^1.1.0",