visit(node) {
    switch (node.type) {
      case 'rule':
      case 'comment':
      case 'charset':
      case 'namespace':
      case 'media':
      case 'import':
      case 'document':
      case 'keyframes':
      case 'page':
      case 'host':
      case 'supports':
        var name = node.type[0].toUpperCase() + node.type.slice(1);
        return this['visit' + name](node);
      case 'font-face':
        return this.visitFontFace(node);
    }
  }
Visit `node`.

@param {*} node
@return {String}
@api private