In starting work on bug 1498604, I had to regenerate package-lock.json, which broke ESLint / Babel in various ways due to the parser implementations having changed, and seemingly Babel's module sub-dependencies conflicting when they shouldn't.

The easiest way out of this seems to be to just update everything that we can at the moment - this doesn't hurt anyway, as we've not had an update for a while.

Some notes:

• Various babel modules have moved to being developed as part of Babel core. Hence the changes to migrate to the @babel/ prefixes.
• eslint-plugin-jest can't be updated yet, that seems to conflict with the devtools debugger package/top-level set up. It could be that we can just disable one rule, but I've left it out for now.
• Due to the way the latest babel parser code is working, I'm having to change tools/lint/eslint/eslint-plugin-mozilla/lib/helpers.js to specify the config file to load. I think we can do that mozilla-central only, from a quick test in thunderbird-conversations it works fine that way.

Try push: https://treeherder.mozilla.org/jobs?repo=try&revision=cb9a7c024e9b687fa16428f050e760f61eb33ab3&selectedTaskRun=ae-72kBLQDqHh6Gkd6J8Yg.0

Newtab failed, but I've fixed that since.

https://hg.mozilla.org/mozilla-central/rev/d7a73176c8cc