dillon1000/react

support ReactDOM.render(..., document) without crashing (#26129)

as reported in #26128 `ReactDOM.render(..., document)` crashed when
`enableHostSingletons` was on. This is because it had a different way of
clearing the container than `createRoot(document)`. I updated the legacy
implementation to share the clearing behavior of `creatRoot` which will
preserve the singleton instances.

I also removed the warning saying not to use `document.body` as a
container