Two possible improvements to the stylelint config:

1. use stylelint-prettier to replace most stylelint formatting rules
2. lint a few more files (from packages/devtools-*)

@jasonLaster, you set up Prettier for CSS initially, do those changes look good to you?

Formatting

We have:

• a bunch of formatting rules in .stylelintrc;
• Prettier that formats CSS (since prettify css #3187).

Both are close but not identical, and at least one file had conflicts in how it handles long selectors. Prettier would wrap those selectors using continuation indents, and stylelint would complain if you used its "indentation" rule with any value.

Turns out we can use stylelint-prettier to take care of the formatting issues. 80% of our stylelint rules basically say whether to put a space before or after language punctuation.

Only downside I've found: the reported errors are a bit more arcane. Not the exact errors, just quoting from the top of my mind:

• Before: Unexpected space character after "{" (name-of-rule-heere)
• After: Replace "." with "" (prettier/prettier)
  (Both report the file:line:column in the same way.)

Linting more files

Can we lint CSS files in packages/devtools-*/src/**/*.css?

In my tests it works pretty well, only requires a few fixes to align with Prettier rules.

We can add them to bin/prettier.js too.

Finally, out of the three stylesheets listed in .stylelintignore, two don't exist anymore and one doesn't have linting issues, so I figured we could just remove this file.