PopulateReferenceMaps caches an iterator for the reference maps list,
which allows skipping many iterations when the live ranges are mostly
sorted.

When they are not sorted however, the complexity increases significantly
since we have to iterate from the beginning of the reference maps list
for each live range.

We observed a real-world wasm GC function where this phase takes up 90%
of the compilation time because of this, which drops to below 2% when
the ranges are sorted first.

R=sigurds@chromium.org
CC=​​jkummerow@chromium.org

Change-Id: I829c909c06e5a1daee0f8d10c156d0a382af9ed0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2985339
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75420}