R1:f6622f43e6d1

Replace all array_combine(x, x) with array_fuse(x) in Phabricator

Summary: Fixes various array_combine() warnings for PHP < 5.4

Test Plan: lint/unit/grep

Reviewers: btrahan, vrana, chad

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D4660