fix(Portal): blur activeElement children when unmounting

[joshblack]

Context https://github.com/github/issues/issues/10142

Update our Portal behavior to check for an activeElement and, if it has one, blur the element. This seems to help address a timing issue where we are removing a portal and focusing an element like in the linked issue.

Specifically, in Safari it seems that even though we restore focus that it doesn't restore the page position without going through this.

Changelog

New

Changed

• Update Portal to blur activeElement children when removing an element

Removed

Rollout strategy

• Patch release

Testing & Reviewing

• Visit the default SelectPanel storybook
• Add enough content on the page to cause it to scroll
• Observe that dismissing the SelectPanel with escape does not cause the page to scroll

[changeset-bot]

🦋 Changeset detected

Latest commit: a2f7940

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Patch

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[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	88.01 KB (-0.03% 🔽)
packages/react/dist/browser.umd.js	88.34 KB (-0.03% 🔽)

[siddharthkp]

Good digging!

This feels like a hack but a very nicely self-contained hack, so happy to ship it if it fixes a bug for us

Let's test this with dotcom to make sure there are no regressions (maybe a good candidate to discuss staff shipping)

[joshblack]

Following up, this fails downstream tests suite typically with an act() violation error 🤔 So it may be that this change is causing effects to happen where they do not typically in these downstream tests and they need act() to remedy it.