message: add m + p utils to CounterLabel
diff: import React from 'react'
  import PropTypes from 'prop-types'
  import classnames from 'classnames'
  +import {mapWhitespaceProps} from './props'
  -export default function CounterLabel({theme, children}) {
  - return <span className={classnames('Counter', theme && `Counter--${theme}`)}>{children}</span>
  +export default function CounterLabel(props) {
  + const {theme, children, className} = mapWhitespaceProps(props)
  + return <span className={classnames(className, 'Counter', theme && `Counter--${theme}`)}>{children}</span>
  }
  CounterLabel.propTypes = {
  