Using webcomponentsjs polyfill makes RxJS callbacks run outside NgZone on Safari

[aabluedragon]

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[X] bug report => search github for a similar issue or PR before submitting
[ ] feature request
[ ] support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question

Current behavior
Including the webcomponentsjs polyfill versions <=0.7.24 (for usage with Polymer1 paper-elements) makes RxJS callbacks (e.g subscribe, map) execute outside NgZone.

Expected behavior
RxJS callbacks should execute inside NgZone.

Minimal reproduction of the problem with instructions

1. Install webcomponentsjs polyfill version <=0.7.24 (issue does not reproduce on 1.0.0-rc-6, but it can't be used with Polymer1).
2. Add script in index.html: <script src="bower_components/webcomponentsjs/webcomponents.min.js"></script>
3. Bootstrap angular2 after the WebComponentsReady event.

window.addEventListener('WebComponentsReady', () => {
  // bootstrap angular2 here
});

4. Execute RxJS post, notice the callback is executed outside NgZone:

this.http.post('http://jsonplaceholder.typicode.com', {}).subscribe((res)=>{
      NgZone.assertInAngularZone(); // fail
    },(err)=>{
      NgZone.assertInAngularZone(); // fail
    });

I've prepared a sample project on github to demonstrate this issue: https://github.com/aabluedragon/safari-ngzone-issue

Also posted on stackoverflow: http://stackoverflow.com/q/42700937/230637

What is the motivation / use case for changing the behavior?
Usage with Polymer1 (for polymer elements, such as paper-elements).

Please tell us about your environment:
macOS Sierra 10.12.3, Webstorm, npm, Polymer1.

• Angular version: 2.4.9

• Browser:
  Works fine on Chrome, issue happens in Safari only.

• Language:
  Typescript

• Node (for AoT issues): node --version = v7.7.1

[JiaLiPassion]

@aabluedragon , thank you for posting the issue, and the reproduce repo. the reason seems to be in Safari, XMLHttpRequest define addEventListener in XMLHttpRequestEventTarget prototype without using EventTarget's.
I will try to fix it.

[JiaLiPassion]

dist.zip
@aabluedragon , you can try this one.

[aabluedragon]

@JiaLiPassion Thanks, it works as expected 👍