Allow reserved words as keys in ES6 module context

`<script type="module">` and *node*/*iojs* code imply full support of ES5. Code transpiled by *babel* is also perfecly safe: ```js $ cat <<––– | babel const superman = { default: { clark: 'kent' }, private: true }; ––– "use strict"; var superman = { "default": { clark: "kent" }, "private": true }; ```

Author: Tomek Wiszniewski

README.md

@@ -140,7 +140,7 @@
  const item = {};
  ```
 
- - [3.2](#3.2) <a name='3.2'></a> Don't use [reserved words](http://es5.github.io/#x7.6.1) as keys. It won't work in IE8. [More info](https://github.com/airbnb/javascript/issues/61).
+ - [3.2](#3.2) <a name='3.2'></a> If your code will be executed in browsers in script context, don't use [reserved words](http://es5.github.io/#x7.6.1) as keys. It won't work in IE8. [More info](https://github.com/airbnb/javascript/issues/61). It’s OK to use them in ES6 modules and server-side code.
 
  ```javascript
  // bad