Similar to https://crrev.com/c/1781047, WordEqual already does the right
truncation in the instruction selector.

Bug: v8:8948
Change-Id: I92e74bafab6a467aeca1570494e9044f9cf18c46
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1781049
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63504}