Function async1

test/processor.test.ts:239–249

(css: Root)

  let starts = 0
  let finish = 0
  let async1 = (css: Root): Promise<void> =>
    new Promise<void>(resolve => {
      starts += 1
      setTimeout(() => {
        equal(starts, 1)

        css.append('a {}')
        finish += 1
        resolve()
      }, 1)
    })
  let async2 = (css: Root): Promise<void> =>
    new Promise<void>(resolve => {
      equal(starts, 1)