simulateSystem(timeToSimulate) {
    const dtFixed = 1.0 / 60.0;
    const dtDiv = timeToSimulate / dtFixed;
    const steps = Math.floor(dtDiv);
    for (let i = 0; i < steps; i++) {
      if (this._parent == null) {
        break;
      } else {
        this.update(dtFixed);
      }
    }
  }
Simulates a particle system for a given duration.
NOTE: systems attempt to update at a rate of 60 fps, so be very careful about how long you simulate
@param {Number} timeToSimulate duration in seconds to simulate