R1:022ac73d607f

Fix iphone scrolling behavior on homepage

Summary: I see a flash of white on my iPhone emulator and on the actual device when I scroll down. Make the texture bigger to prevent it.

Test Plan: Scrolled on emulator, no more white flash.

Reviewers: chad

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D5416