Bundled Themes: Twenty Eleven & Twenty Twelve dropdown category widget exceeds...

Bundled Themes: Twenty Eleven & Twenty Twelve dropdown category widget exceeds parent div when strings are long enough.

Fixes the width of the category dropdown by limiting the width of `select` items in widgets using `max-width: 100%`.

Props gma992, karmatosed.
Fixes #37926.
Built from https://develop.svn.wordpress.org/trunk@47801


git-svn-id: https://core.svn.wordpress.org/trunk@47577 1a063a9b-81f0-0310-95a4-ce76da25c4cd