Revert "Remove legacy www config from Rollup build"

[bvaughn]

Reverts #18016

This change caused a Makehaste failure for syncs:

Cannot transform 'shared/react/ReactEventsFocus-dev.js': TypeError: Unsupported function type: ObjectMethod
...

The specific syntax change that causes the failure is going from this:

var Focus = (Object.freeze || Object)({
  passiveBrowserEventsSupported: passiveBrowserEventsSupported,

to this:

var Focus = Object.freeze({
  get passiveBrowserEventsSupported() {
    return passiveBrowserEventsSupported;
  },

[sizebot]

No significant bundle size changes to report.

Size changes (stable)

Generated by 🚫 dangerJS against f0f60e6

[sizebot]

No significant bundle size changes to report.

Size changes (experimental)

Generated by 🚫 dangerJS against f0f60e6

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit f0f60e6:

Sandbox	Source
jovial-pike-x07zu	Configuration

[bvaughn]

Closing in favor of #18022