I am getting the error "Promise is Undefined" in IE11 in my react app. When I am using Worker in my code

```
const worker = new Worker('./worker.ts')
console.log('worker' , worker);

```

When I check logs in Chrome and IE 11 Chrome returns worker onMessage as function whereas IE 11 returns null and I also see message "Permission denied". I also gets this error in IE 11 "Promise is Undefined".

I have imported import 'babel-polyfill' in the beginning of the file. All other Promises are working fine except this Worker.

How can I fix this?