pause() {
    var entities;
    var i;
    var key;
    if (!this.isPlaying) {
      return;
    }
    this.isPlaying = false;

    // Sleep all components.
    for (key in this.components) {
      this.components[key].pause();
    }

    // Tell all child entities to pause.
    entities = this.getChildEntities();
    for (i = 0; i < entities.length; i++) {
      entities[i].pause();
    }
    this.emit('pause');
  }
Pause dynamic behavior associated with entity such as dynamic components and animations.
Tell all children entities to also pause.