This avoids the performance overhead of the function call every time `dirname( __FILE__ )` was used instead of `__DIR__`.
This commit also includes:
* Removing unnecessary parentheses from `include`/`require` statements. These are language constructs, not function calls.
* Replacing `include` statements for several files with `require_once`, for consistency:
* `wp-admin/admin-header.php`
* `wp-admin/admin-footer.php`
* `wp-includes/version.php`
Props ayeshrajans, desrosj, valentinbora, jrf, joostdevalk, netweb.
Fixes#48082.
git-svn-id: https://develop.svn.wordpress.org/trunk@47198 602fd350-edb4-49c9-b593-d223f7449a82
Fixes a bug where the UI wasn't updated after deleting/updating a theme.
Also introduces unit tests for theme management ajax handlers. For now they're
focused on `wp_ajax_update_theme()` but they can include tests for other
handlers as well.
Props chrisjean for initial patch.
Fixes#37924.
git-svn-id: https://develop.svn.wordpress.org/trunk@38710 602fd350-edb4-49c9-b593-d223f7449a82