Remove `IntegerDivisionByZeroException`

[lrhn]

Just make it an ArgumentError. It doesn't deserve its own class.

[srawlins]

Should we mark IntegerDivisionByZeroException deprecated so we can delete in Dart 3 without fanfare?

[lrhn]

I still think we should, but it's not decided that it's worth the pain.

[lrhn]

The class is now deprecated, but not removed.

[leafpetersen]

Should we stop using this in the core libraries now, or do you propose to make that switch later?

[lrhn]

The current state throws an IntegerDivisionByZeroException which implements StateError and Exception.
That makes it backwards compatible (anyone catching IntegerDivisionByZeroException or Exception will still catch it.
They will get warning if using IntegerDivisionByZeroException, but not if just catching Exception.
Because of that, it would be nice to stop throwing an Exception entirely.

Our breaking-change policy makes it a breaking change to change the throw-behavior of something unless it throws an Error, and it used to be just an Exception, so we probably do have to go through the breaking change process.
I think it'll be a painless breaking change (except for some amount of tests that change behavior - I highly doubt anyone ever catches that exception outside of tests.

We can go for an intermediate state where IntegerDivisionByZeroException becomes a (deprecated) type alias for StateError.
That will keep code working, but stop actually having the class.