Add support for optional chaining and nullary coalescing

[lissitz]

Last discussion: #7246
Today both proposals reached stage 3. Could this be considered again?

[jasonmcaffee]

Proposal status updated here:
https://github.com/tc39/proposal-optional-chaining

[iansu]

Yes, I think now that it's reached stage 3 we would be willing to include it.

[jflayhart]

Specifically: tc39/proposal-optional-chaining@9948e3d#diff-3540caefa502006d8a33cb1385720803

I’m happy to submit a PR!

Edit: Nvm, someone beat me to it: #7438

[jpangelle]

Now that TypeScript 3.7 released, prettier/prettier#6657 was merged, typescript-eslint/typescript-eslint#1045 was merged, and babel/babel#10269 was merged, can we merge facebook/create-react-app#7438 soon? It doesn't seem there are any more blockers.

Edit: Looks like prettier plans to release tomorrow, November 8, 2019.

[evankennedy]

They did the thing! (sorry for spam, I totally haven't been pressing the refresh button all day even though I'm subscribed for release notices)

[danny-does-stuff]

Is there a plan for when this feature will be available? Does create-react-app v3.3 have an expected release date?