This value is now redundant - it is always the same as regular offset.

TEST=angle_end2end_tests
BUG=angleproject:956

Change-Id: If4b6c8bcbebf24fbf84723fe081fd058916cc504
Reviewed-on: https://chromium-review.googlesource.com/262423Reviewed-by: Nicolas Capens <capn@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>