No need to reassign those JSTypedArrays.

Bug: v8:6704
Change-Id: Ide1f8bb119285b57ea85b8e710358c917244f801
Reviewed-on: https://chromium-review.googlesource.com/641474
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47693}