The FastArray path for Array#groupBy and Array#groupByToMap does not
recheck the input array's length each iteration. This is incorrect since
the grouping callback can truncate the length, and we should deopt to the
generic path when this happens.

Bug: chromium:1312838, v8:12499
Change-Id: Id3a4973e9960500a2f29ed63281ea721777d4dd3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3570342Reviewed-by: Marja Hölttä <marja@chromium.org>
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79787}