This part of the change removes default value support from ModelBinding.
Updated some unit tests to verify that it does nothing in that case.
Deleted a functional test as it was pure duplication of another
(supported) case where the property has a pre-initialized value.
This change adds support for our three-valued logic to the default value
handling part of the MutableObjectModelBinder.
The issue is that we want to look up a default value when a 'greedy' model
binder returns true but doesn't find a value.
We also don't want to call the property setter unless there is:
1). A value from model binding OR
2). A default value
See #1695 for a detailed explanation. This change builds support into the
system for the case that a model binder returns true without setting a
value for the Model.
In this case, validation will be skipped if it's a top-level object.
Note that explicitly setting null will still run validation.
Ryan Nowak
N. Taylor Mullen
Ajay Bhargav Baaskaran
Harsh Gupta