window.addEventListener not patched on Safari

[alxhub]

Simple repro: https://plnkr.co/edit/OtpOVa9pXJBWRfoBe0OP?p=preview

Result on Chrome:

window.addEventListener function addEventListener(){return f(this, arguments)}

div.addEventListener function addEventListener(){return f(this, arguments)}

Result on Safari:

window.addEventListener function addEventListener() { [native code] }

div.addEventListener function addEventListener(){return f(this, arguments)}

Note that window.addEventListener is unpatched.

This is for zone.js 0.6.12 release.

[mhevery]

@alxhub could you create a PR?