Replace deprecated initCustomEvent with CustomEvent

[saul-atomrigs]

Summary

Hello React Team,
I propose replacing the deprecated initCustomEvent with CustomEvent.

Documentations:

• initCustomEvent(deprecated): https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/initCustomEvent
• CustomEvent(recommended): https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/CustomEvent

Thank you 😄

[react-sizebot]

Comparing: 4a36d3e...2ae4392

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	=	1.83 kB	1.83 kB
oss-stable/react-dom/cjs/react-dom-client.production.js	=	516.14 kB	516.14 kB	=	91.87 kB	91.87 kB
oss-experimental/react-dom/cjs/react-dom.production.js	=	6.69 kB	6.69 kB	=	1.83 kB	1.83 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js	=	621.45 kB	621.45 kB	=	110.00 kB	110.00 kB
facebook-www/ReactDOM-prod.classic.js	=	654.82 kB	654.82 kB	=	115.57 kB	115.57 kB
facebook-www/ReactDOM-prod.modern.js	=	645.10 kB	645.10 kB	=	114.04 kB	114.04 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 2ae4392