Add a focus outline to the widget control toggle arrows. Fixes #27953. Props TomHarrigan.

git-svn-id: https://develop.svn.wordpress.org/trunk@29983 602fd350-edb4-49c9-b593-d223f7449a82
Avoid double path separators in `load_theme_textdomain()`. Fixes #29122. Props bradyvercher

git-svn-id: https://develop.svn.wordpress.org/trunk@29984 602fd350-edb4-49c9-b593-d223f7449a82