Remove redundant test steps (#26161)

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## Summary

This TODO mentions an issue with JSDOM that [seems to have been
resolved](https://github.com/jsdom/jsdom/pull/2996).

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## How did you test this change?

- Ensured that the `document.activeElement` is no longer `node` after
`node.blur` is called.
- Verified that the tests still pass.
- Looked for [a merged PR that fixes the
issue](https://github.com/jsdom/jsdom/pull/2996).

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