@babel/polyfill deprecated since babel v7.4.0

[0xdevalias]

https://babeljs.io/docs/en/next/babel-polyfill

As of Babel 7.4.0, this package has been deprecated in favor of directly including core-js/stable (to polyfill ECMAScript features) and regenerator-runtime/runtime (needed to use transpiled generator functions)

In our project we have already moved to this new recommended method, but webpacker is causing us to pull down @babel/polyfill still.

It would be cool to somehow remove the direct dependency on @babel/polyfill so we can use our own.

It's included here: https://github.com/rails/webpacker/blob/master/package.json#L22

[jakeNiemiec]

Also see: #2031

[aried3r]

Can this be closed? Ping @gauravtiwari