function makeTextContent(textContent) {
	  // NOTE: Null values reduce hidden classes.
	  return {
	    type: 'TEXT_CONTENT',
	    content: textContent,
	    fromIndex: null,
	    fromNode: null,
	    toIndex: null,
	    afterNode: null
	  };
	}
Make an update for setting the text content.

@param {string} textContent Text content to set.
@private