Ensure we globally replace [ and ] in customizer control IDs, to match the PHP.

props westonruter.
fixes #25238.


git-svn-id: https://develop.svn.wordpress.org/trunk@25680 602fd350-edb4-49c9-b593-d223f7449a82
When determining a frontend, local URL in the theme customizer, match the home URL without a trailing slash.

props SergeyBiryukov.
fixes #25315.


git-svn-id: https://develop.svn.wordpress.org/trunk@25681 602fd350-edb4-49c9-b593-d223f7449a82