Almost every method in `wp_xmlrpc_server` can also return `IXR_Error` and should be labeled as such. Rehabilitate some `return` syntax.

See #30224.


git-svn-id: https://develop.svn.wordpress.org/trunk@30181 602fd350-edb4-49c9-b593-d223f7449a82
In `WP_Comment_Query`, declare `$query_vars` and `$comments` as properties.

See #30224.


git-svn-id: https://develop.svn.wordpress.org/trunk@30182 602fd350-edb4-49c9-b593-d223f7449a82
In `WP_Locale`, declare `$number_format` as a property.

See #30224.


git-svn-id: https://develop.svn.wordpress.org/trunk@30183 602fd350-edb4-49c9-b593-d223f7449a82
In `WP_Tax_Query`, declare `$primary_table` and `$primary_id_column` as properties.

See #30224.


git-svn-id: https://develop.svn.wordpress.org/trunk@30184 602fd350-edb4-49c9-b593-d223f7449a82