fix(AjaxObservable): support withCredentials for CORS request

[kwonoj]

Description:

This PR updates AjaxRequest accepts withCredentials flag to be used when create CORS request by setting crossDomain, replicating RXJS-DOM implementation.

Related issue (if exists):

closes #1732, #1711

[coveralls]

Coverage decreased (-0.1%) to 96.247% when pulling 58ee4ce on kwonoj:dom-crossdomain into 01df713 on ReactiveX:master.

[benlesh]

Looks like there are some new code branches that are not covered.

https://coveralls.io/builds/6534299/source?filename=src%2Fobservable%2Fdom%2FAjaxObservable.ts#L33

[kwonoj]

Yes it is, it was bit tough to cover all cases. I'll try to update them.

[kwonoj]

Updated couple of test cases to cover basic scenarios of XHR creation.

[coveralls]

Coverage increased (+0.1%) to 96.46% when pulling 97ca7e8 on kwonoj:dom-crossdomain into 01df713 on ReactiveX:master.

[coveralls]

Coverage increased (+0.1%) to 96.46% when pulling 8084572 on kwonoj:dom-crossdomain into 0a6c4e8 on ReactiveX:master.

[kwonoj]

I think change's ok, will check in around on this Sunday to next Monday if there isn't any suggestions.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.