This fixes a non-determinism issue caused by the cache being full.
Depending on the non-deterministic value of the handles in HeapConstant
nodes, different cache entries would be overwritten in this case.

The old implementation of NodeCache had a fixed limit, overwriting
entries when the cache is full. This behavior didn't really make sense,
but the hand-written hash map implementation couldn't handle arbitrary
numbers of hash collisions, so removing the limit wasn't an option either.
Thus this CL just replaces the custom hash map with a normal
std::unordered_map, that is, a ZoneUnorderedMap.

Bug: chromium:1046815
Change-Id: I95269f2b1068eb9dfe3ee2ab5cca1cb460bc8fa3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2087405Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66592}