Bump @babel/core from 7.3.4 to 7.4.0 in /js

Bumps [@babel/core](https://github.com/babel/babel) from 7.3.4 to 7.4.0.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/compare/v7.3.4...v7.4.0)

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

js/package.json

@@ -22,7 +22,7 @@
     "ui-select": "^0.19.8"
   },
   "devDependencies": {
-    "@babel/core": "^7.3.4",
+    "@babel/core": "^7.4.0",
     "@babel/polyfill": "^7.2.5",
     "@babel/preset-env": "^7.3.4",
     "babel-loader": "^8.0.5",