Dead code in `wp-admin/includes/file.php`:
* In `wp_handle_upload()` and `wp_handle_sideload()`, `$ext` gets conditionally reset... and then is never used.
* In `request_filesystem_credentials()`, `$password` is initialized as an empty string. The variable is never used.

See #27882.



git-svn-id: https://develop.svn.wordpress.org/trunk@28268 602fd350-edb4-49c9-b593-d223f7449a82
Customizer: Only tie header button action events to the header controls.

props danielbachhuber.
fixes #28046. see #27848.


git-svn-id: https://develop.svn.wordpress.org/trunk@28269 602fd350-edb4-49c9-b593-d223f7449a82