1881697 - [meta] Replace ESLint environment support

Status: NEW

(Developer Infrastructure :: Lint and Formatting, task, P3)

Description

[Mark Banner (:standard8)]

ESLint v9 is dropping support for environments, which means we'll need to find other ways of defining groups of globals for particular files.

On the most part, we can do this by file paths or using special naming conventions. We've already started doing this for workers for example (bug 1847110).

This meta will probably be broken down into several parts:

• Replace in-line /* eslint-env mozilla/chrome-script */ definitions with automatic injection of globals if SpecialPowers.loadChromeScript is detected.
• Investigate if there's other in-line definitions that could be replaced in similar ways.
• Rename files / improve handling of environments, so that in-line eslint-env definitions are no longer required at all.
  • In a few cases it may make sense to use /* global ... */ but I'd like to generally avoid that if possible as that would require more maintenance.

We should be ending up with a ESLint system where the existing environments are not being used, and it is mainly hidden "behind the scenes".