function makeInsertMarkup(markup, afterNode, toIndex) {
	  // NOTE: Null values reduce hidden classes.
	  return {
	    type: 'INSERT_MARKUP',
	    content: markup,
	    fromIndex: null,
	    fromNode: null,
	    toIndex: toIndex,
	    afterNode: afterNode
	  };
	}
Make an update for markup to be rendered and inserted at a supplied index.

@param {string} markup Markup that renders into an element.
@param {number} toIndex Destination index.
@private