Revisit @babel/present-env browserslist polyfills

Created by: esetnik

Is this a bug report?

No

In the babel-preset-react-app project https://github.com/facebook/create-react-app/blob/master/packages/babel-preset-react-app/create.js#L92 it specifically overrides the browserslist configuration and targets ie 9 with useBuiltIns: false. I believe this should be revisited as a configuration option to avoid the requirement for most people to eject create-react-app to run it in production. It seems that the configuration would be much nicer if we could avoid having to include polyfills manually and instead use browserslist configuration with @babel/preset-env and @babel/polyfill to do the heavy lifting. Then you'd only need to import @babel/polyfill in the top of the index.js file (could be included by default with a sensible default browserslist configuration) and you'd automatically get all of the polyfills needed. If this idea is of interest, i'd be happy to submit a PR with the required changes.