[compiler] Use kAssumeMemoryFence to create refs for bytecode constants

The BytecodeArray itself was fetched by using a barrier so all reads
from the constant pool are safe.

Bug: v8:7790
Change-Id: If924d43a10c7aa20b69225fab8219e7bd988419c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2903149
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74654}