Split the parameter-dependent and parameter-independent validation.
This will more easily let us cache independent validation in Context.

Bug: angleproject:2747
Change-Id: I78a12798cd03a398392ca213bf51e2079295b97e
Reviewed-on: https://chromium-review.googlesource.com/1158610
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Frank Henigman <fjhenigman@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>