Fix call to scrollToPosition()

Summary: See rPea67a8ab8e58. This was typed wrong and all the things I tested called scrollToPosition() directly.

Test Plan: Quoted a comment.

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley, krzysztof.ciebiera

Differential Revision: https://secure.phabricator.com/D11505