GeneralizeField already calculates the field owner.

Change-Id: I0730471479d4289d3d027ea63178ddae659ee2b2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2507717
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70891}