Disallow TODO comments
Background
According to our coding style:
Don't add TODO comments, create an issue and reference it in a comment instead.
We already disallow TODO comments in JavaScript files but not yet in CSS files.
See also trac#7434.
What to change
Add the following rule to stylelint-config-eyeo:
"comment-word-blacklist": ["TODO", "FIXME"]
The values are case-sensitive so we may want to use a regular expression instead.