Require Node.js 10

[stasm]

All fluent.js packages currently require node >= 8.9.0, which ceased to be the active LTS as of January 2019. The new LTS is Node.js 10 which will remain active until April 2020. See https://github.com/nodejs/Release.

Node.js 10 ships with a native implementation of Intl.PluralRules. We currently use an outdated polyfill which diverges from the spec when it comes to formatting numbers with fractions.

We would also be able to remove two Babel plugins from our testing setup: @babel/plugin-proposal-async-generator-functions and @babel/plugin-proposal-object-rest-spread.

[stasm]

We should be careful to not break the consumers of our packages. In particular, addons-linter used by web-ext still target Node.js 8. @EnTeQuAk are you aware of any plans to move to Node.js 10 now that it's the current active LTS?

[EnTeQuAk]

As far as I know web-ext isn't planning to do that move anytime soon, so is addons-linter.

cc @rpl though for clarification.

[stasm]

My main reason for filing this issue was to be able to drop the outdated polyfill and use the native PluralRules implementation available in Node.js 10. Unfortunately it seems like the current implementation of PluralRules in Chrome is buggy; @zbraniecki has filed https://bugs.chromium.org/p/v8/issues/detail?id=8866 about it. So we might want to continue using the polyfill for the time being. I filed eemeli/intl-pluralrules#2 to ask if the polyfill could be updated to match the spec wrt. minimumFractionDigits.

[stasm]

@EnTeQuAk Thanks, that's good to know. We might want to stick to Node.js 8 for now then.

[stasm]

It looks like addons-linter and web-ext both require Node.js 10 now:

• Update to node 10 mozilla/addons-linter#2912
• chore: Upgrade to node 10 mozilla/web-ext#1731

According to https://nodejs.org/en/about/releases/ Node.js 8 will be EOL-ed on 31st of December, 2019, which would make January a good time to drop it from Fluent as well.