Remove dead property caching code.
Remove dead property caching code.

In Ids, we were permanently caching computed properties, but none of
the tests actually predicated on this. We may want to add this back in
the future, but then again, maybe not.

If a computed property operates on a cached value, like a query, then
while the query will not be stable, the objects contained in the query
will. This is why the tests are passing, and why this can safely be
removed for now.

cowboyd/microstates.js