This change fixes call sites on the main request path for a simple site
(model binding, validation, views) that allocate boxed list enumerators.
Some cases aren't addressed by this change because the fix is too invasive
or requires changing an important contract to take IList instead of
IEnumerable. Will follow up on those case by case in order of importance.
Abstractions - Core MVC extensibility
Controllers - MVC implementations of .Abstractions and supporting
contracts
Infrastructure - General purpose support APIs. Metadata APIs that don't
fit clearly with a feature or with .Abstraction
Ryan Nowak
Pranav K
Doug Bunting