Support nullish coalescing

[domoritz]

Feature Use Case

I would like to use nullish coalescing documented at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing_operator.

Feature Proposal

export const c = a ?? b;

Should compile to

const c = a ?? b;

export { c };

Related issue: #3469

[lukastaegert]

Apparently, nullish coalescing has already been merged upstream and is just waiting to be released. For a month now 🙄 acornjs/acorn#890

But I guess we could switch to a direct Github build of acorn until then.

[hardfist]

@lukastaegert It seems that acorn nullish coalescing coalescing has released