Zero handleId returned by setImmediate()

[gkalpak]

RxJS version:
6.0.0-uncanny-rc.7 (probably present since 6.0.0-alpha.1

Code to reproduce:
We ran into it by using an internal property:

import {asapScheduler} from 'rxjs';
...
if (asapScheduler.scheduled) {
  // Not reaching this line if `scheduled === 0`.
}

Additional information:
The internal implementation of setImmediate() returns a zero handleId the first time it is called. Although there is no official spec for setImmediate(), one would expect that the returned value would be similar to those of setTimeout() and setInterval(), which are both non-zero positive integers.

Furthermore, the return value is used by AsapScheduler's AsapAction, which checks it for truthy-ness and "re-schedules" with setImmediate() if it is falsy (e.g. 0).

This seems to have been broken in 5eb6af7.

I am not sure if this can actually break something.
We were bitten by it in angular.io, because we were using the internal scheduled property (which is assigned the handleId returned by setImmediate()) and checking it for truthy-ness. It is easy for us to work-around, but bringing it up in case it might actually break something (by calling setImmediate() more then once).

[benlesh]

It seems like there's two things that need to happen here:

1. We can make the setImmediate (which is an abandoned API now, AFAIK), return an id starting at 1.
2. We need to deprecate these properties as no one should be using them.

[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.