ResumeGenerator is semantically a successor of SuspendGenerator (for
reasoning about liveness), but operationally it's a successor of
SwitchOnGeneratorState. This means that the jump to ResumeGenerator will
always create a new basic block, even if the SuspendGenerator was dead.

This causes problems if we made other assumptions on liveness based on
the semantics; in particular, we assume that JumpLoop is dead if the
loop header is dead (thanks to loop irreducibility).
SwitchOnGeneratorState breaks irreducibility, and this manifests as the
JumpLoop being alive and trying to jump to a dead header.

Since this is a special case, and loops are otherwise irreducible, we
can also fix it with a special case; namely, MarkBytecodeDead now has a
special case for SuspendGenerator which manually advances the iterator
and kills the ResumeGenerator.

Bug: v8:7700
Change-Id: Ice162f061e7ba1dda7ceb4f6fe9234889655b417
Fixed: v8:13250
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3865556Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82931}