add(decl, prefix) {
    let p = decl.prop
    if (p.includes('mask')) {
      if (prefix === '-webkit-' || prefix === '-webkit- old') {
        return super.add(decl, prefix)
      }
    } else if (
      p === 'list-style' ||
      p === 'list-style-image' ||
      p === 'content'
    ) {
      if (prefix === '-webkit-' || prefix === '-webkit- old') {
        return super.add(decl, prefix)
      }
    } else {
      return super.add(decl, prefix)
    }
    return undefined
  }
Do not add non-webkit prefixes for list-style and object