- ensure `ViewDataDictionary` constructors are not passed a `null` or
`Mock.Of<IModelMetadataProvider>()` instance
- `ViewDataDictionary` constructors always use the `IModelMetadataProvider`
- `viewData.ModelMetadata` now never `null`
- `ViewDataDictionary<int>.Model` no longer throws if read before it's written
- `ViewDataDictionary.ModelMetadata` now copied to new instances in fewer cases
- e.g. don't use unusual `object` datatype with customized `ModelMetadata`
* Introducing RazorPage and RazorPageOfT that represent the Razor
execution aspect of view execution. Moving view execution hierarchy behavior
(Layout, partial views etc) into a separate RazorView type.
* Renaming IVirtualPathViewFactory to IRazorPageFactory,
IRazorViewActivator to IRazorPageActivator
* Renaming VirtualPathViewFactor to FileBasedPageFactory to
correctly reflect what it does.
Fixes#814
Doug Bunting
Pranav K