This simplifies the code for the ordered enum cases. Also sort the
existing non-ordered enums alphabetically.

Bug: angleproject:2574
Bug: angleproject:2169
Change-Id: I444092a94ee46f76b2fc05a557458f273c5a50bc
Reviewed-on: https://chromium-review.googlesource.com/1067111
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>