Add SuspenseList to DevTools Element Names

[sebmarkbage]

react/packages/react-devtools-shared/src/utils.js

Line 491 in 49af889

return 'Suspense';

We have SuspenseList for the tree view but not when printing JSX.

When we fallthrough here we call getDisplayName with a symbol, because we assume that if it's not a string, then it's a function. We should be checking whether it is a function before calling getDisplayName.

Subsequently if we call getDisplayName with a symbol we get the error invalid value used as weak map key which messes up things after that. I think that's the actual cause of #19364

[bpernick]

@sebmarkbage I'm happy to take this on if you like! Just to clarify, what would be the expected behavior of calling getDisplayNameForReactElement on a symbol? Returning 'Symbol'?

Also should we handle the case where it falls through and is neither a symbol nor a function? In this case should it simply return 'Anonymous'?

[bpernick]

Sorry for any confusion earlier! I just took a stab at adding SuspenseList and adding a check to only pass functions into getDisplayName. (I've submitted my CLA)