Method to implement ArrayAccess for keys formerly returned by get_themes().
Author, Author Name, Author URI, and Description did not previously return translated data. We are doing so now as it is safe to do. However, as Name and Title could have been used as the key for get_themes(), both remain untranslated for back compatibility. This means that [‘Name’] is not ideal, and care should be taken to use
$theme::display( 'Name' ) to get a properly translated header.