Also drive-by adds a test for toSpliced on an empty array.

Bug: chromium:1367651, v8:12764
Change-Id: I59ff19ef73dd6c5ea972dc6f39f1968858099ef8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3919870
Commit-Queue: Adam Klein <adamk@chromium.org>
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83441}