Method pushState

testing/fake-dom.js:587–600

* @param {?Object} state * @param {?string} title * @param {?string} url * @param {boolean=} opt_fireEvent

(state, title, url, opt_fireEvent)

   * @param {boolean=} opt_fireEvent
   */
  pushState(state, title, url, opt_fireEvent) {
    this.index++;
    if (this.index < this.stack.length) {
      // Remove tail.
      this.stack.splice(this.index, this.stack.length - this.index);
    }
    this.stack[this.index] = {
      state: state ? freeze(state) : null,
      url,
    };
    if (opt_fireEvent) {
      this.win.eventListeners.fire({type: 'popstate'});
    }
  }

  /**
   * @param {?Object} state