Drive-by Torque changes:
  - kSize can be non-aligned, use SizeFor() instead for map allocation.
  - Factory functions use Torque-generated setters directly to work even
    if they are shadowed.
  - Allow class generation in the presence of custom weak fields, this
    was supported already.


Bug: v8:7793
Change-Id: I7e2df45d550ff70973e5167459050fd84db03114
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2547285
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Seth Brenith <seth.brenith@microsoft.com>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71371}