Eliminate use of `extract()` in `wp_list_categories()`. 

See #22400.

Built from https://develop.svn.wordpress.org/trunk@28434


git-svn-id: http://core.svn.wordpress.org/trunk@28261 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Eliminate use of `extract()` in `wp_generate_tag_cloud()`. 

See #22400.

Built from https://develop.svn.wordpress.org/trunk@28435


git-svn-id: http://core.svn.wordpress.org/trunk@28262 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Eliminate use of `extract()` in `Walker_Category::start_el()`. 

See #22400.

Built from https://develop.svn.wordpress.org/trunk@28436


git-svn-id: http://core.svn.wordpress.org/trunk@28263 1a063a9b-81f0-0310-95a4-ce76da25c4cd