POT, generated from r23404
Begin simplifying some of the visual elements in the admin, starting with gradients. White space purposefully not currently altered. props lessbloat, melchoyce, aaroncampbell, sabreuse. see #23415.
Compress scripts/styles: 3.6-alpha-23408.
Restore the following:

* Box shadow for screen options/help tabs focus state.
* Text shadow on the about screen badge to match the text shadow in the graphic itself.
* Border for credits screen gravatars, in place of the previous box shadow.

props nacin. see #23415.