This follows a convention from RxJS where observable creators allow passing a scheduler (e.g. fromPromise, of, empty, ...)

Setting the default scheduler to asyncScheduler has the same effect as the delay(0) which is why it was removed.

…duler

And add tests to verify behavior

…sions

BREAKING: fromRef() observables are no longer multicasted by default

…chronously, invoke zone task if unsubscribed before first emission