Add brackets to visually distinguish show more / show less text

app/assets/javascripts/components/components/status_content.jsx

@@ -88,7 +88,7 @@ const StatusContent = React.createClass({
     const spoilerContent = { __html: emojify(status.get('spoiler_text', '')) };
 
     if (status.get('spoiler_text').length > 0) {
-      const toggleText = hidden ? <FormattedMessage id='status.show_more' defaultMessage='Show more' /> : <FormattedMessage id='status.show_less' defaultMessage='Show less' />;
+      const toggleText = hidden ? <FormattedMessage id='status.show_more' defaultMessage='[Show more]' /> : <FormattedMessage id='status.show_less' defaultMessage='[Show less]' />;
 
       return (
         <div className='status__content' style={{ cursor: 'pointer' }} onMouseDown={this.handleMouseDown} onMouseUp={this.handleMouseUp}>