R1:321df38ccf2e

Deleting unused private member variable from AphrontRequest

Summary: I was poking around to see how this class worked and noticed this variable does nothing.

Test Plan: Careful inspection and reasoning that unused private member variable can be deleted.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3068