Eliminate use of `extract()` in `wp_xmlrpc_server::mw_editPost()` (MetaWeblog API, y'all). 

A lot of the extracted variables are overwritten by being explicitly set later. 
Only set variables that would otherwise not be present with `compact()` is called.

See #22400.

Built from https://develop.svn.wordpress.org/trunk@28448


git-svn-id: http://core.svn.wordpress.org/trunk@28275 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Eliminate use of `extract()` in `wp_widget_rss_form()`.

See #22400.

Built from https://develop.svn.wordpress.org/trunk@28449


git-svn-id: http://core.svn.wordpress.org/trunk@28276 1a063a9b-81f0-0310-95a4-ce76da25c4cd