Got an error  'SCRIPT5009 Map is undefined' in IE10

Hi,  since `redux-action` is updated to `2.6.1`, I got an error  "SCRIPT5009 Map is undefined" in IE10.

Error got in file `utils/isMap.js`:

```javascript
export default value => value instanceof Map;
```

Should I add `Map` polyfill to my repo ?

Thanks.