This CL:
 - stops tracking transitions for fast maps that are known to be detached
 - reuses descriptor arrays when transitioning detached maps to avoid O(n^2) performance and garbage creation

Fix2 in reland: constructor_or_backpointer can be a smi since it can also hold a user-provided function.prototype
Fix in reland: check whether the map of the back pointer is the metamap rather than reading the map of the constructor-or-backpointer slot. If the slot contains a constructor, it's possible that the object transitions while the concurrent marker is reading the map (from which it's reading the instance type); and it's possible that the transitioned map isn't set up yet fully when we read the instance type. An acquire load for the constructor-or-backpointer map would also fix it by serializing stores, but is more expensive. Checking the metamap is faster.

Original commit message:
> This avoids an O(n^2) algorithm that creates an equal amount of garbage.
> Even though the actual final descriptor array might be a little bigger,
> it reduces peak memory usage by allocating less.

Change-Id: Id99dc76a369057e5c4d76a31163605cb38a66867
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2172080Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67501}