The previous combination of a conditional and an unconditional move
produced an incorrect value when dst == rhs and lhs contained the
expected result.

Fixed: chromium:1338980
Change-Id: If3f722999ed9c0ffd687736280d048d232d75736
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3738219
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81475}