This works around a bug on Adreno 3xx in which array varying variables
are assigned in the reverse order.

BUG=chromium:709317

Change-Id: I86a345747f293ca8a2cb9a281bd1b752e66dcd3a
Reviewed-on: https://chromium-review.googlesource.com/475979
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>