Unaligned access is still unused, but will be necessary to load String-length
once we store it as an int32 next to the hash-field.

Bug: v8:7065
Change-Id: I7fa9364e062774c0a6b32e7f961031dcd30c564c
Reviewed-on: https://chromium-review.googlesource.com/763349
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49358}