Bump @babel/preset-env from 7.8.4 to 7.8.6 in /js

Bumps [@babel/preset-env](https://github.com/babel/babel) from 7.8.4 to 7.8.6.
- [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/v7.8.4...v7.8.6)

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

js/package.json

@@ -29,7 +29,7 @@
     "@babel/core": "^7.8.4",
     "@babel/plugin-syntax-dynamic-import": "^7.8.3",
     "@babel/polyfill": "^7.8.3",
-    "@babel/preset-env": "^7.8.4",
+    "@babel/preset-env": "^7.8.6",
     "babel-loader": "^8.0.6",
     "css-loader": "^3.4.2",
     "karma": "^4.4.1",