R1:fcc7dbbf1511

Fix a few minor JSHint warnings

Summary: Basically, don't assign expressions to a variable if the variable is unused.

Test Plan: `arc lint`

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11072