Convert refs to createRoot

[eps1lon]

No description provided.

[eps1lon]

We can't test this with the new API since root.render does not return the instance so I copied the original test into refsLegacy-test.js.

[rickhanlonii]

you can get the instance by doing instance = this in cDM, not great but we're doing it a lot elsewhere.

[eps1lon]

And that would test cDM matches ref.

But not what ReactDOM.render returns. result wasn't about getting the instance. We already have inst which is set from the ref spy. result was used here to check that expect(ReactDOM.render(<div ref={current => (instance = current)})).toBe(instance).

[react-sizebot]

Comparing: 3d9b201...9c6819a

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	=	176.24 kB	176.24 kB	=	54.88 kB	54.88 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	178.34 kB	178.34 kB	=	55.53 kB	55.53 kB
facebook-www/ReactDOM-prod.classic.js	=	571.94 kB	571.94 kB	=	100.56 kB	100.56 kB
facebook-www/ReactDOM-prod.modern.js	=	555.70 kB	555.70 kB	=	97.62 kB	97.62 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 9c6819a