Returns the metaDescription, includes the date if it is set.

@private
@this SnippetPreview

@returns {string} The meta data for the analyzer.
function() {
	var metaDesc = this.data.metaDesc;

	if ( isEmpty( metaDesc ) ) {
		metaDesc = this.opts.defaultValue.metaDesc;
	}

	if ( this.hasPluggable() ) {
		metaDesc = this.refObj.pluggable._applyModifications( "data_meta_desc", metaDesc );
	}

	if ( ! isEmpty( this.opts.metaDescriptionDate ) && ! isEmpty( metaDesc ) ) {
		metaDesc = this.opts.metaDescriptionDate + " - " + this.data.metaDesc;
	}

	return stripSpaces( metaDesc );
}