Changeset 31730 for trunk/tests/phpunit/tests/admin/includesListTable.php

Introduce a new algorithm for displaying a hierarchical list of post objects in the WP_Posts_List_Table. This reduces processing time, reduces database queries, and substantially reduces memory use on sites with a high number of Pages.

Props nofearinc, rodrigosprimo, nacin, johnbillion.
Fixes #15459