So far creating scripts always grew the script_list without ever
reusing cleared slots or shrinking. While this is probably not a
problem with script_list in practice, this is still a memory leak.

Fix this leak by using WeakArrayList::Append instead of AddToEnd.
Append adds to the end of the array, but potentially compacts and
shrinks the list as well. Other WeakArrayLists can use this method as
well, as long as they are not using indices into this array.

Bug: v8:10031
Change-Id: If743c4cc3f8d67ab735522f0ded038b2fb43e437
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1967385
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65640}