This reverts commit 0637eac3.
It's considered a spec bug:
https://cvs.khronos.org/bugzilla/show_bug.cgi?id=8656

Change-Id: Id49121d5adf91ecab3d261c3c12e2f879f47e856
Reviewed-on: https://swiftshader-review.googlesource.com/5192Reviewed-by: Shannon Woods <shannonwoods@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>