[fix] replace polyfill.io with cloudflare equivalent

[tnfssc]

Summary

This PR will replace the reference to polyfill.io with a Cloudflare equivalent. This is needed because polyfill.io was bought by a Chinese company and started serving malware embedded in the polyfill JS files.

Source: https://sansec.io/research/polyfill-supply-chain-attack

How did you test this change?

I ran the command yarn dev in fixtures/dom directory. I opened http://localhost:3000/hydration?version=15.0.0-rc.2 on my browser. I checked if the page works like before. And if the polyfill.min.js was loaded using the developer tools. Attached the screenshot for the same.

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
react-compiler-playground	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 28, 2024 4:30am

[react-sizebot]

Comparing: e02baf6...a650163

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.js	=	6.68 kB	6.68 kB	+0.11%	1.83 kB	1.83 kB
oss-stable/react-dom/cjs/react-dom-client.production.js	=	497.99 kB	497.99 kB	=	89.27 kB	89.27 kB
oss-experimental/react-dom/cjs/react-dom.production.js	=	6.69 kB	6.69 kB	+0.05%	1.83 kB	1.83 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js	=	502.81 kB	502.81 kB	=	89.97 kB	89.97 kB
facebook-www/ReactDOM-prod.classic.js	=	597.08 kB	597.08 kB	=	105.33 kB	105.33 kB
facebook-www/ReactDOM-prod.modern.js	=	571.42 kB	571.42 kB	=	101.27 kB	101.27 kB
test_utils/ReactAllWarnings.js	Deleted	62.88 kB	0.00 kB	Deleted	15.69 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	62.88 kB	0.00 kB	Deleted	15.69 kB	0.00 kB

Generated by 🚫 dangerJS against a650163

[eps1lon]

Thank you