This was incorrectly acquiring every plane to texture 0.

BUG=angleproject:1332

Change-Id: I6df1401b705d903078e2631634b6bf20a07570de
Reviewed-on: https://chromium-review.googlesource.com/342513Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: John Bauman <jbauman@chromium.org>