Normally, taking a heap snapshot in the near heap limit would
result in a full GC, then the overhead of the promotions would
cause another invocation of the heap limit callback and it can
raise the limit in the second call to avoid an OOM, so we test
that the callback can indeed raise the limit this way in this
case. When there is only one generation, however, there would
not be the overhead of promotions so the callback may not be
triggered again during the generation of the heap snapshot.
In that case we only need to check that the callback is called
and it can perform GC-triggering operations jsut fine there.

Bug: v8:12815
Change-Id: If244417624b56bc068aed480fb3391d26c19005a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3600357Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Joyee Cheung <joyee@igalia.com>
Cr-Commit-Position: refs/heads/main@{#80094}