The last step in array.splice slow-path is to update length of the array https://cs.chromium.org/chromium/src/v8/src/builtins/array-splice.tq?rcl=59a29d88cc5972d2323a80a70de19ffd2812e5e4&l=349. For sealed object, it should be nop.

Bug: chromium:951164
Change-Id: I0c3098526c7df6c4dd734dd6c79cc0bba3b9b213
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1559217
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60793}