withCredentials not enabled for sync requests

[benjefferies]

withCredentials doesn't seem to work when making a sync request. It looks to be brought in by this commit 6783dc2. Firefox must have been crashing for sync requests when withCredentials: true was enforced.

Searching around it looks like there are ways of fixing it as suggested in this stackoverflow post https://stackoverflow.com/a/16673436.

[naugtur]

Thanks for letting us know.
Want to try coding it up?