Suspending inside a hidden tree should not cause fallbacks to appear

[acdlite]

If something suspends inside a hidden tree, it should not affect anything in the visible part of the UI. This means that Offscreen acts like a Suspense boundary whenever it's in its hidden state.

[sizebot]

Comparing: c1f5884...27f8b68

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	+0.01%	131.79 kB	131.80 kB	+0.01%	42.40 kB	42.41 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	+0.01%	137.06 kB	137.07 kB	+0.01%	44.00 kB	44.00 kB
facebook-www/ReactDOM-prod.classic.js	+0.02%	457.38 kB	457.49 kB	+0.03%	83.24 kB	83.26 kB
facebook-www/ReactDOM-prod.modern.js	+0.02%	442.62 kB	442.73 kB	+0.03%	80.96 kB	80.98 kB
facebook-www/ReactDOMForked-prod.classic.js	+0.94%	458.15 kB	462.44 kB	+0.72%	83.35 kB	83.94 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
facebook-www/ReactDOMForked-prod.modern.js	+0.97%	443.40 kB	447.68 kB	+0.80%	81.07 kB	81.72 kB
facebook-www/ReactDOMForked-profiling.modern.js	+0.96%	473.55 kB	478.12 kB	+0.85%	85.60 kB	86.33 kB
facebook-www/ReactDOMForked-profiling.classic.js	+0.94%	488.38 kB	492.95 kB	+0.77%	87.96 kB	88.64 kB
facebook-www/ReactDOMForked-prod.classic.js	+0.94%	458.15 kB	462.44 kB	+0.72%	83.35 kB	83.94 kB
facebook-www/ReactDOMForked-dev.modern.js	+0.59%	1,162.06 kB	1,168.95 kB	+0.47%	256.35 kB	257.55 kB
facebook-www/ReactDOMForked-dev.classic.js	+0.58%	1,185.68 kB	1,192.57 kB	+0.45%	260.85 kB	262.03 kB

Generated by 🚫 dangerJS against 27f8b68

[rickhanlonii]

Reviewed together offline, lgtm