Revert the fixed-with tick and convert tests counting on it to `future`.

Ticks for models are deprecated, so we don't want to add new
functionality. The reflector would like to have flexibility to alter the
tick interval on slow networks, so the interval can't be known to
models.

Views primarily need to know when the simulation time has changed since
the simulation state won't change otherwise. `setTimeout` and
`setInterval` are available for views to use for other timing needs.