The ParameterModel and ParameterDescriptor have had a notion of
optionality for a while now, even though all parameters are treated as
'optional' in MVC.
This change removes these settings. Optionality for overloading in webapi
compat shim is reimplemented via a new binder metadata.
- #EngineeringDay
- VS does not yet format auto-properties nicely; reverted what it did
Also revert changes under
- test/Microsoft.AspNet.Mvc.Razor.Host.Test/TestFiles