Differential Revision: https://phabricator.services.mozilla.com/D176637

Bug 1725934 - Remove unnecessary babel plugin, and update node modules to the latest versions. r=Mardak

plugin-syntax-class-properties was supported by default in Babel 7.14.0.
This also adds top level await support in modules with the upgrade to Babel 7.15.0.

Differential Revision: https://phabricator.services.mozilla.com/D122865

Bug 1702166 - Update ESLint, Babel and associated modules to the latest versions. r=mossop,nchevobbe

Differential Revision: https://phabricator.services.mozilla.com/D110606

Differential Revision: https://phabricator.services.mozilla.com/D84820

Bug 1617959: Switch to the babel-eslint parser and turn on support for optional chaining and nullish coalescing operator syntaxes. r=Standard8

The babel-eslint parser defaults to assuming all scripts are modules. Although
we're moving in that direction it seems reasonable to set the default as regular
scripts for now. All the places that were previously overriding the parser are
already specifying the sourceType in their eslint configs.

I chose to put the babel config in a file that babel itself won't look to avoid
the risk of this config impacting the use of babel elsewhere in the tree.

Differential Revision: https://phabricator.services.mozilla.com/D66127

--HG--
extra : moz-landing-system : lando

Differential Revision: https://phabricator.services.mozilla.com/D67319

--HG--
extra : moz-landing-system : lando