☂️ Suspense umbrella task

[bvaughn]

Misc

• Keyboard navigation: Arrow key navigation for selected element is a bit broken. You can use down/right arrow to drill down into a Suspense component, but the up/left arrows won't drill back up. (It gets stuck at the component beneath Suspense.)
  

Hiding timed-out children

react/react/pull/13823 changed the behavior of timed-out suspense trees. In order to preserve state (of both React components and host components) the timed-out tree now stays mounted, but gets hidden (e.g. "display: none").

For the GIF below, I used create-react-app with the following changes: https://gist.github.com/bvaughn/aab2a855c5fa1daa9ca55b1fdfac20a5

• If the suspended subtree is expanded in the DevTools tree view, it gets auto-collapsed when it's hidden.
  

• The Profiler's render counter gets reset for all components in the hidden subtree. This makes it look like it's a new tree and might be confusing to people.

Testing

TODO @bvaughn and @acdlite will fill this in later.

[swyxio]

would this be a nice to have? #1141

[bvaughn]

Not sure. DevTools is already monstrously large. Don't know how I feel about adding more panels and increasing scope until/unless we tackle something like #1214

[bvaughn]

Fixes went out with 3.4.3