Byte offset can be outside of Smi range and must be loaded as a Number
rather than a Smi.

Bug: chromium:852258
Change-Id: Ida6e07ba68a050d4f5a9f28500986cc67c619b4c
Reviewed-on: https://chromium-review.googlesource.com/1100886Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53748}