The invariant is that Map::bit_field2 shouldn't change, and the
IsInRetainedMapListBit apparently changes when the map is held
weakly from optimized code. This causes TurboFan compilations to
change the Map::Hash() result, which in turn causes lookups on
the normalized map cache to miss (and maybe other bad consequences).

With this change we swap Map::IsInRetainedMapListBit (previously in
bit_field2) and Map::HasHiddenPrototypeBit (previously in bit_field3)
to address this problem.

Bug: chromium:963411, v8:9114, v8:9267
Change-Id: I040a27c37305fa602649750bd93bee40c91fca78
Cq-Include-Trybots: luci.chromium.try:linux-rel,win7-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1619747
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61657}