Profiles

Mentioned in [58137] on Core SVN:
Users: Add JS confirmation if user profile has unsaved changes.

Mentioned in [58022] on Core SVN:
Upgrade/Install: Validate source & destination values in `WP_Ugrader`.

Mentioned in [56993] on Core SVN:
Build/Test tools: Introduce partial unit tests for `WP_Upgrader`.

Mentioned in [56992] on Core SVN:
Build/Test tools: Introduce partial unit tests for `WP_Upgrader`.

Mentioned in [53460] on Core SVN:
General: Remove redundant `ltrim()` from `path_join()`.

Mentioned in [53457] on Core SVN:
Tests: Add unit tests for `path_join()`.

Created ticket #55897 on Core Trac:
Add tests for path_join()