Fix LTR field handling:
 * Restore .ltr class lost in the conversion to RTL as a build process.
 * Make email and url inputs always LTR.
 * Set an email field on user-edit to be LTR.

props MikeHansenMe, yoavf for initial patches.
fixes #26824.

Built from https://develop.svn.wordpress.org/trunk@27743


git-svn-id: http://core.svn.wordpress.org/trunk@27580 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Themes screens: Bump to 20 items per page so it fills a high resolution display. see #26968.

Built from https://develop.svn.wordpress.org/trunk@27744


git-svn-id: http://core.svn.wordpress.org/trunk@27581 1a063a9b-81f0-0310-95a4-ce76da25c4cd