A simple fix to avoid an unneeded instruction.

R=ahaas@chromium.org

Bug: chromium:1152363
Change-Id: I7188156816ab24ed88fb1cd79859aa9f0b6c948b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2557513Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71367}