Fix some documentation typos in various core files.

Props vlajos.
Fixes #29199.

Built from https://develop.svn.wordpress.org/trunk@29479


git-svn-id: http://core.svn.wordpress.org/trunk@29257 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Plugin details: Remove some CSS rules that were unnecessary and causing issues in Firefox. see #27440.

Built from https://develop.svn.wordpress.org/trunk@29480


git-svn-id: http://core.svn.wordpress.org/trunk@29258 1a063a9b-81f0-0310-95a4-ce76da25c4cd