Function check

test/autoprefixer.test.js:210–216

(from, instance = prefixer(from))

}

function check(from, instance = prefixer(from)) {
  let input = read(from)
  let output = read(from + '.out')
  let result = postcss([instance]).process(input)
  equal(result.warnings().length, 0)
  equal(universalizer(result.css), universalizer(output))
}

const COMMONS = [
  'transition',