Bump @babel/preset-env from 7.2.3 to 7.3.1 in /js

Bumps [@babel/preset-env](https://github.com/babel/babel) from 7.2.3 to 7.3.1.
- [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/v7.2.3...v7.3.1)

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

js/package.json

@@ -24,7 +24,7 @@
   "devDependencies": {
     "@babel/core": "^7.2.2",
     "@babel/polyfill": "^7.0.0",
-    "@babel/preset-env": "^7.2.3",
+    "@babel/preset-env": "^7.3.1",
     "babel-loader": "^8.0.5",
     "css-loader": "^2.1.0",
     "karma": "^3.1.4",