R1:cebe6ac38771

Stylize bubble counts.

Summary: Adds colors to bubble counts in app launcher.

Test Plan: Tested with 0 attention counts, 12 attention counts, and thousands of open tasks.

Reviewers: epriestley, vrana

Reviewed By: vrana

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5090