feat(react-dom): Add hydrateRoot

[eps1lon]

Please fill in this template.

• Use a meaningful title for the pull request. Include the name of the package modified.
• Test the change in your own code. (Compile and run.)
• Add or edit tests to reflect the change.
• Follow the advice from the readme.
• Avoid common mistakes.
• Run npm test <package to test>.

If changing an existing definition:

• Provide a URL to documentation or source code which provides context for the suggested changes:
  • createRoot(..., {hydrate:true}) -> hydrateRoot(...) facebook/react#21687
• [ ] If this PR brings the type definitions up to date with a new version of the JS library, update the version number in the header.

[typescript-bot]

@eps1lon Thank you for submitting this PR!

This is a live comment which I will keep updated.

1 package in this PR

• react-dom — on npm, on unpkg (author is owner)

Code Reviews

Because this is a widely-used package, a DT maintainer will need to review it before it can be merged.

You can test the changes of this PR in the Playground.

Status

• ✅ No merge conflicts
• ✅ Continuous integration tests have passed
• ✅ Most recent commit is approved by a DT maintainer

All of the items on the list are green. To merge, you need to post a comment including the string "Ready to merge" to bring in your changes.

---

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[typescript-bot]

🔔 @MartynasZilinskas @theruther4d @Jessidhia — please review this PR in the next few days. Be sure to explicitly select Approve or Request Changes in the GitHub UI so I know what's going on.

[typescript-bot]

@eps1lon Everything looks good here. Great job! I am ready to merge this PR (at cbc7715) on your behalf.

If you'd like that to happen, please post a comment saying:

Ready to merge

and I'll merge this PR almost instantly. Thanks for helping out! ❤️

(@MartynasZilinskas, @theruther4d, @Jessidhia: you can do this too.)

[eps1lon]

Ready to merge

[typescript-bot]

I just published @types/react-dom@17.0.8 to npm.