Previously the flag would only disable the check in the case we tried to use newer tsc version.
In g3 we sometimes take a while to update tsc, but as a prerequisite of that Angular needs to be
updated first. This change enables us to update Angular and use it in g3 while g3 is being update
to the required tsc. Of course extra care is required when this check is disabled, but since we
control everything in g3, it's on us to get this right.
I don't see any preexisting tests for this, and I'm not sure how to write them right now.
I filed https://github.com/angular/angular/issues/22699
PR Close#22669
3f70aba272