The check here doesn't make sense because it's testing the behavior of
another method. The best way to check identity is but checking the
`#object_id` of an object - thus, this check actually does what the test
says it does.

In some cases --- like writing meta-extensions of `IndifferentAccess`
--- we need access to the ability to convert a key for the purposes of
`IndifferentAccess`. Exposing this behavior as a module function makes
this possible.

When exporting a Dash via `#to_h` or `#to_hash`, we expect all
properties to be exported whether or not they are set. However, in the
change that allows codependent properties to be nilified, we regressed
the behavior of exporting all properties.

There is a gotcha here, which I note in the tests for the specs. For
posterity, MRI does not send the `#to_hash` method to anything that
subclasses `Hash` when you double-splat it. Thus, we cannot override the
behavior within MRI. For more information, see [this comment][1] where I
detail the behavior of double-splat within MRI.

Currently, JRuby also follows this behavior, but it's not guaranteed
that other Rubies will.

[1]: hashie#353 (comment)

… into michaelherold-dash-nil-keys