lib/rules/no-unsupported-features.js
function isIgnored(key, ignores) {
    return (
        ignores.indexOf(key) !== -1 ||
        FEATURES[key].alias.some(alias => ignores.indexOf(alias) !== -1)
    )
}
function isIgnored(key, ignores) {
    return (
        ignores.indexOf(key) !== -1 ||
        FEATURES[key].alias.some(alias => ignores.indexOf(alias) !== -1)
    )
}
Checks whether a given key should be ignored or not.

@param {string} key - A key to check.
@param {string[]} ignores - An array of keys and aliases to be ignored.
@returns {boolean} `true` if the key should be ignored.