visitKeyframes(node) {
    var buf = this.indent + '@keyframes ' + node.name;
    buf += '\n';
    ++this.indents;
    for (var i = 0, len = node.keyframes.length; i < len; ++i) {
      buf += this.visitKeyframe(node.keyframes[i]);
    }
    --this.indents;
    return buf;
  }
Visit Keyframes `node`.`

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