Team Update: Browsing Buddies

Our first cycle ended successfully on the 9th, with a first patch for Infinite Scroll on Themes screens (#19815) committed on time.

The task for our next cycle is Multiple Screenshots for Themes (#19816), and helenyhou has been spending time creating comps.  Additional comps still welcomed at Make UI.

The rest of the time was spent on polishing the code for Infinite Scroll for the Themes screens, including prevention of loading themes.js on unnecessary tabs, throttling for the scroll event, general cleanup, and a move to use Deferred for AJAX requests.  Feedback and JS review welcomed on #19815.