code: function (child, node) {
  	      var update = this.removeChild(child, node);
  	      child._mountIndex = null;
  	      return update;
  	    }
docs: Unmounts a rendered child.
  
  NOTE: This is part of `updateChildren` and is here for readability.
  
  @param {ReactComponent} child Component to unmount.
  @private