Tests for Async-from-Sync Iterator changes

[mhofman]

https://github.com/tc39/ecma262/pull/2600 reached consensus at the last plenary. It updates Async-from-Sync Iterator objects to close the wrapped iterator in cases where the async wrapper is considered to be done, but the sync iterator isn't.

I included some examples in the presentation of where this behavior shows up, and there were a few relevant cases in the linked issue. I plan to adapt those into test262 cases, but I may not have time immediately, so creating this issue to keep track of the tests needed.