Initialize bit field in map using relaxed store

Restore of https://chromium-review.googlesource.com/c/v8/v8/+/2194012.
I changed it to be non-atomic and missed the fact that the concurrent
marker accesses the has_prototype_slot concurrently.

Bug: v8:7790, v8:11353
Change-Id: I292aeacb340b6340c40b633db2591c7d0cbca3bb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2772608Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73531}

src/objects/map.cc

@@ -1441,7 +1441,7 @@ Handle<Map> Map::RawCopy(Isolate* isolate, Handle<Map> map, int instance_size,
   Handle<HeapObject> prototype(map->prototype(), isolate);
   Map::SetPrototype(isolate, result, prototype);
   result->set_constructor_or_back_pointer(map->GetConstructor());
-  result->set_bit_field(map->bit_field());
+  result->set_relaxed_bit_field(map->bit_field());
   result->set_bit_field2(map->bit_field2());
   int new_bit_field3 = map->bit_field3();
   new_bit_field3 = Bits3::OwnsDescriptorsBit::update(new_bit_field3, true);