/node_modules/babel-polyfill/node_modules/core-js/library/modules/es6.weak-set.js

 1'use strict';
 2var weak = require('./_collection-weak');
 3var validate = require('./_validate-collection');
 4var WEAK_SET = 'WeakSet';
 5
 6// 23.4 WeakSet Objects
 7require('./_collection')(WEAK_SET, function (get) {
 8  return function WeakSet() { return get(this, arguments.length > 0 ? arguments[0] : undefined); };
 9}, {
10  // 23.4.3.1 WeakSet.prototype.add(value)
11  add: function add(value) {
12    return weak.def(validate(this, WEAK_SET), value, true);
13  }
14}, weak, false, true);