`Map[@@toStringTag]` 的初始值是"Map".

`Map.prototype[@@toStringTag]` 属性的属性特性：
writable | false
enumerable | false
configurable | true

## 语法

    Map[Symbol.toStringTag]

## 示例

    Object.prototype.toString.call(new Map()) // "[object Map]"

## 规范

Specification | Status | Comment
--- | --- | ---
ECMAScript 2015 (6th Edition, ECMA-262) Map.prototype[@@toStringTag] | Standard | Initial definition.
ECMAScript Latest Draft (ECMA-262) Map.prototype[@@toStringTag] | Draft |

## 浏览器兼容

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

- Desktop
- Mobile

Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari
--- | --- | --- | --- | --- | ---
Basic support | 44.0 | 未实现 | 未实现 | 未实现 | 未实现

Feature | Android | Android Webview | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android
--- | --- | --- | --- | --- | --- | --- | ---
Basic support | 未实现 | 44.0 | 未实现 | 未实现 | 未实现 | 未实现 | 44.0