"Cannot set property once" error when used with zone.js

### Description

When used with zone.js (all Angular applications), following error is thrown:

```
zone.js:1953 Uncaught TypeError: Cannot set property once of [object Object] which has only a getter
at HTMLDivElement.addEventListener (zone.js:1953:42)
at webcomponents-bundle.js:98:596
at webcomponents-bundle.js:98:767
at webcomponents-bundle.js:382:176
```

### Steps to reproduce

Generate an Angular app and include this polyfill. Start the app.

I've verified that adding a `once` setter removes the error.

#### Expected behavior

Should not throw error

#### Actual behavior

Above error is thrown

### Version

This was introduced in version 2.7 by this PR https://github.com/webcomponents/polyfills/pull/469

### Browsers affected

Only tested on Chrome