The store element handlers don't check if the array length is writable
before updating the length. Since this is not expected to be a common
case no need of handling this in the element handlers. Just moving to
megamorphic would be sufficient.

Bug: chromium:967104
Change-Id: I7a7f9ea768266b9ffd6289328d61d2297d455619
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1658154
Commit-Queue: Mythri Alle <mythria@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62152}