Android Edge: This site has been updated in background

### [REQUIRED] Describe your environment

* Operating System version: Android 10 QQ1B.191205.011
* Browser version: Edge 42.0.4.4062
* Firebase SDK version: 7.6.1
* Firebase Product: messaging

### [REQUIRED] Describe the problem

#### Steps to reproduce:

- Set up Service Worker with the default non-GCM JS
- Send notification
- Chrome desktop gets the notification as expected
- Android Chrome gets the notification as expected
- Edge shows "This site was updated in the background"

#### Relevant Code:

We use the following Service Worker:
```javascript
importScripts('https://www.gstatic.com/firebasejs/7.6.1/firebase-app.js');
importScripts('https://www.gstatic.com/firebasejs/7.6.1/firebase-analytics.js');
importScripts('https://www.gstatic.com/firebasejs/7.6.1/firebase-messaging.js');
firebase.initializeApp({
apiKey: "...",
authDomain: "...",
projectId: "...",
messagingSenderId: "...",
appId: "...",
});
const messaging = firebase.messaging();
```
This works perfectly fine in Chrome, but strangely enough Edge doesn't seem to receive the notification payload.