remove TODOs

I would like to discuss these TODOs. They fall into the following categories:

  - things we once wanted to do but no longer want to do (remove these);
  - things we once wanted to do and still want to do (create issues for these); and
  - questions (discuss these).

i think this is fine--IIRC his objection was to making a distinction between `{x: undefined}` and `{}` which is not really meaningful here. The test `assert.strictEqual(R.where(spec, test1), true);` captures what we want the behavior to be.