Check compatibility with latest Angular (v11)

[pomek]

A similar to CKEditor 4 (ckeditor/ckeditor4-angular#148).

[pomek]

Blindly estimating as 0.5 in case if changes in docs will be required.

[pkwasnik]

There are two issues with zone.js (possibly not blocking the upgrade):

• During the update process angular requires zone.js in version "~0.10.3". After that update, I've updated zone.js to "~0.11.3" and haven't noticed any issues during tests.
• Problem with importing zone.js the same as in the past described here: Angular 8: ngOnDestroy crashes when targeting es2015 or greater #109. The solution from Angular 8: ngOnDestroy crashes when targeting es2015 or greater #109 (comment) fixes the problem: in polyfills.js import zone.js using import 'zone.js/dist/zone.js' instead of import 'zone.js'. But anyway there should be created an issue for zone.js about that.

[ma2ciek]

I've checked and the Zone.js 0.11 breaking changes are described here - https://github.com/angular/angular/tree/master/packages/zone.js#breaking-changes-since-zonejs-v0111.

Anyway, could you create an issue in Zone.js for the found regression and link it here?

[ma2ciek]

So, to finish this task we need to:

• report the regression to the Angular (zone.js) team,
• document this common issue and a workaround in docs

Apart from that the code in the PR looks good and is ready to merge 👍