weakmap allowed primitive key

weakdict.js

function WeakDict() {
	var map = WeakMap();
	Object.defineProperty(map, '__dict__', {
		value: Object.create(null),
		writable: true,
		configuable: true,
	});
	map.__proto__ = WeakDict.prototype;
	return map;
}
WeakDict.prototype = Object.create(WeakMap.prototype, {
	constructor: {
		value: WeakDict,
		writable: true,
		configuable: true,
	},
	has: {
		value: function has(key) {
			if (key instanceof Object)
				return WeakMap.prototype.has.apply(this, arguments);

			return key in this.__dict__;
		},
		writable: true,
		configuable: true,
	},
	get: {
		value: function get(key, def) {
			if (key instanceof Object)
				return WeakMap.prototype.get.apply(this, arguments);

			return key in this.__dict__ ? this.__dict__[key] : def;
		},
		writable: true,
		configuable: true,
	},
	set: {
		value: function set(key, val) {
			if (key instanceof Object)
				return WeakMap.prototype.set.apply(this, arguments);

			return this.__dict__[key] = val;
		},
		writable: true,
		configuable: true,
	},
	delete: {
		value: function delete(key) {
			if (key instanceof Object)
				return WeakMap.prototype.delete.apply(this, arguments);

			var has = key in this.__dict__;
			delete this.__dict__[key];
			return has;
		},
		writable: true,
		configuable: true,
	},
});