Convert useFocusWithin to createRoot

[eps1lon]

No description provided.

[react-sizebot]

Comparing: 9aef5d2...4b3f5a9

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	176.59 kB	176.59 kB	=	55.01 kB	55.01 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	178.69 kB	178.69 kB	=	55.64 kB	55.64 kB
facebook-www/ReactDOM-prod.classic.js	=	573.52 kB	573.52 kB	=	100.99 kB	100.99 kB
facebook-www/ReactDOM-prod.modern.js	=	557.29 kB	557.29 kB	=	98.07 kB	98.07 kB
test_utils/ReactAllWarnings.js	Deleted	67.55 kB	0.00 kB	Deleted	16.54 kB	0.00 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
test_utils/ReactAllWarnings.js	Deleted	67.55 kB	0.00 kB	Deleted	16.54 kB	0.00 kB

Generated by 🚫 dangerJS against 4b3f5a9

[eps1lon]

Matches other testing patterns e.g.

react/packages/react-dom/src/__tests__/ReactTestUtilsAct-test.js

Lines 773 to 777 in a8875ea

	// resolve the promise
	await act(async () => {
	resolved = true;
	resolve();
	});

Without also ensuring we don't throw the promise, we end up in an infinite loop and ultimately crash with RangeError: Potential infinite loop: exceeded 1500 iterations.

[rickhanlonii]

Makes sense, the infinite loop error is because of the root.render(null); in the after each. If we flush here, it would be good to assert on the output:

Suggested change

	});
	});
	expect(container2.innerHTML).toBe('<div><input style=""></div>');