Upgrade Rollup

[mmarkelov]

Working on upgrading rollup - some test builds show decreasing in size of bundles.
But also there are some problems with it:

1. The legacy option is now deprecated, so is it critical for building react ?
   I checked this issue - and it tells that it's totally fine.
2. There are couples circular dependency warnings with ReactFiberScheduler.js and also some default' is not exported warnings

You also can check my branch
Maybe you can help me with it

So what do you think about this? Does that make sense?

[TrySound]

WIP in #13356 #13321

[mmarkelov]

@TrySound, just didn’t see these prs ( My mistake. If you need some help about this I’ll be happy to help you

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contribution.

[stale]

Closing this issue after a prolonged period of inactivity. If this issue is still present in the latest release, please create a new issue with up-to-date information. Thank you!