acorn 8, esm, mocha

[mbostock]

This:

• Upgrades to Acorn 8, fixing Class fields support #64.
• Upgrades yarn.lock.
• Changes the default ecmaVersion from 12 to 13.
• Adopts ES modules, replacing standard-things/esm.
• Adopts Mocha, replacing Tap.
• Adopts ESLint in GitHub actions.
• Requires Node 14+.
• Drops experimental parseModule functionality.

We could do this change more minimally, but I think we’re going to want to do this in the near future anyway, so we might as well tie breaking changes together to minimize the number of major version bumps.

[mbostock]

If you want to compare to the pre-Tap snapshots of yore:

812e84e~...mbostock/update-acorn

[sydneypalumbo]

sorry I've been slow to get to this! one thing I just wanted to call out is that we do use peekId when constructing document history currently in order to get cell names (we could either remove that logic now or do a normal parse if we wanted to keep it)

[mbostock]

Okay, I’ll restore the peekId functionality.

[mbostock]

Okay @sydneypalumbo this should be ready for another look! Thanks.

[sydneypalumbo]

👍