Don't consider Portals animating unless they're wrapped in a ViewTransition

[sebmarkbage]

And that doesn't disable with update="none".

The principle here is that we want the content of a Portal to animate if other things are animating with it but if other things aren't animating then we don't.

[react-sizebot]

Comparing: 3a5b326...88362e6

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	+0.05%	1.83 kB	1.83 kB
oss-stable/react-dom/cjs/react-dom-client.production.js	=	529.74 kB	529.74 kB	=	93.49 kB	93.49 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	=	651.70 kB	651.42 kB	+0.03%	114.70 kB	114.74 kB
facebook-www/ReactDOM-prod.classic.js	=	675.93 kB	675.67 kB	+0.02%	118.81 kB	118.83 kB
facebook-www/ReactDOM-prod.modern.js	=	666.21 kB	665.95 kB	+0.02%	117.18 kB	117.20 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 88362e6

[jackpope]

Synced this and it tested well internally. New semantics make more sense too. Thanks!