Carrots are awesome with vegetables

Summary: Use an angle-down icon instead of hard edged caret for search bar. I tested replacing this globally, but it didn't hold up as well.

Test Plan:
hover states, desktop, tablet, mobile.

{F379596}

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D12521