Someone added a single line breaking change to React's Typedefs causing a worldwide problem for people using @types/react. If this change ever goes in it needs to be at a SemVer version change, not as a patch change...

Note that without this reversion all the React examples (including the one linked below) would actually be wrong as they would need to check for the existence of this.state before using it.

The version number shouldn't be changed as this should be a correction for the previous PR...

Referencing #26813

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• Test the change in your own code. (Compile and run.)
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• Avoid common mistakes.
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Select one of these and delete the others:

If changing an existing definition:

• Provide a URL to documentation or source code which provides context for the suggested changes: https://reactjs.org/docs/state-and-lifecycle.html
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