core-js project provides (as core-js-compat package) all required data about the necessity of core-js modules, entry points, and tools for work with it - it's useful for integration with tools like babel or swc. If you wanna help, you could take a look at the related section of CONTRIBUTING.md. The visualization of compatibility data and the browser tests runner is available here, the example:
Tested in:
- Chrome 26+
- Firefox 4+
- Safari 5+
- Opera 12+
- Internet Explorer 8+ (sure, IE8 with ES3 limitations; IE7- also should work, but no longer tested)
- Edge
- Android Browser 2.3+
- iOS Safari 5.1+
- PhantomJS 1.9+
- NodeJS 0.8+
- Deno 1.0+
- Rhino 1.7.14+
...and it doesn't mean core-js will not work in other engines, they just have not been tested.