Delete unused prototype of "new" change detection primitives.
Delete unused prototype of "new" change detection primitives.

This was deprioritized this quarter, and the code is unused, and unlikely to be something we focus on in the near term, so no reason to make the code base more confusing by having duplicate/unused code.

PiperOrigin-RevId: 271210639

angulardart/angular,angulardart/angular,angulardart/angular