Fix strange header appearance bug

Summary:
Text in the header changes appearance shortly after page loads. This
is due - for some reason - to adding the flash object. Making the width and
height of the flash object 0 solves this.

Test Plan: viewed locally, problem gone

Reviewers: epriestley

Reviewed By: epriestley

CC: allenjohnashton, keebuhm, aran, Korvin

Differential Revision: https://secure.phabricator.com/D2719