make one attr only can be read, but could not be rewrited/ deleted
@param {Object} obj
@param {string} prop
@param {Object} descriptor
@return {descriptor}
function frozen(obj, prop, descriptor) {
  if (descriptor === undefined) {
    /* istanbul ignore else  */
    warn('You are using @frozen on an undefined property. This property will become a frozen undefined forever, which is meaningless');
    return {
      value: undefined,
      writable: false,
      enumerable: false,
      configurable: false
    };
  }
  descriptor.enumerable = false;
  descriptor.configurable = false;
  if (isAccessorDescriptor(descriptor)) {
    var _get = descriptor.get;

    descriptor.set = undefined;
    if (!isFunction(_get)) {
      /* istanbul ignore else  */
      warn('You are using @frozen on one accessor descriptor without getter. This property will become a frozen undefined finally.Which maybe meaningless.');
      return;
    }
    return {
      get: function get() {
        var value = bind$1(_get, this)();
        defineProperty$2$1(this, prop, {
          value: value,
          writable: false,
          configurable: false,
          enumerable: false
        });
        return value;
      },

      set: undefined,
      configurable: false,
      enumerable: false
    };
  }
  // $FlowFixMe: comeon, can disjoint union be reliable?
  descriptor.writable = false;
  return descriptor;
}