function Ticker(numLanes) {
    this._nextStep = null;
    this._lanes = [];
    this._stepQueue = [];
    this._stepCallbacks = {};
    this._step = this._step.bind(this);
    for (var i = 0; i < numLanes; i++) {
      this._lanes.push(new TickerLane());
    }
  }
A ticker system for handling DOM reads and writes in an efficient way.

@class