This CL also gives up trying to maintain double and system word
fields at aligned addresses because currently it's not always
maintained (v8:8875) and Torque object definitions do not support
padding fields (v8:8863).

Given that both platforms where pointer compression is going to be
enabled (x64 and arm64) support loading of doubles and full words
from 4-byte aligned addresses we are fine.

Bug: v8:7703
Change-Id: I99fc6da5a0927f4db9b8fb24c7cc0bfc416523bc
Reviewed-on: https://chromium-review.googlesource.com/c/1496974
Auto-Submit: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60013}