Use `elseif` when slurping the `nonce` in `check_ajax_referer()` to avoid accidentally overwriting it. 

Fail wonderboymusic in [25433].
Props ocean90.
Fixes #25369.
See [25433].


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git-svn-id: http://core.svn.wordpress.org/trunk@25470 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Ensure that terms with a post count of `0` are not returned in `wp_count_terms()` when `hide_empty => true`. Adds unit test which ensures that `wp_count_terms()` returns `0`.

Props markjaquith.
Fixes #15919.


Built from https://develop.svn.wordpress.org/trunk@25551


git-svn-id: http://core.svn.wordpress.org/trunk@25471 1a063a9b-81f0-0310-95a4-ce76da25c4cd