Converting an object to an array length can freeze the array whose
length is being set, but SetLength for the frozen elements accessor
is supposedly unreachable. This fix extends the existing special
handling for suddenly-readonly lengths to cover this case as well.
Prior art: https://codereview.chromium.org/2543553002

Bug: chromium:1044911
Change-Id: I85d2e79446a8d9c1d22cd86ddf828328bf51a1a1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2023555
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66020}