Remove text-rendering CSS rule

Summary: This rule is making text actually more difficult to read on Windows, as well as is broken on Win/Chrome, and evidentally has performance issues on mobile browsers.

Test Plan: Turn it off, can still read web page

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D10940