We can lower the eslint cyclomatic complexity threshold in some directories without adding eslint suppression comments in any .js source files. We need to specify the complexity rule in accessible/.eslintrc because it doesn't inherit the mozilla/recommended rules. eslint's default complexity threshold is 20.
Also bump the eslint-plugin-mozilla version because we modified the mozilla/recommended rules.
MozReview-Commit-ID: 57T4gAjPH7z
Enable the rule with the maximums set to avoid current failures, except for test_form_autocomplete which is very
high (82). The levels are set per major area, with existing warnings being changed to errors.
MozReview-Commit-ID: 37M6Ry0Mr1c
