Intead of checking a series of bools and special variables, organize
the state application into a switch with internal dirty bits. This
should be faster for no-op, and makes it clear where we have to
further optimize the state update to pre-compute certain values.

BUG=angleproject:1156

Change-Id: I8eca8716340499085afa170ff45f7788e84fecab
Reviewed-on: https://chromium-review.googlesource.com/531794
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>