TimelineQueueButtonHeader: make it sticky

app/soapbox/components/timeline_queue_button_header.js

@@ -2,6 +2,7 @@ import React from 'react';
 import PropTypes from 'prop-types';
 import { injectIntl } from 'react-intl';
 import classNames from 'classnames';
+import SvgIcon from 'soapbox/components/svg_icon';
 
 export default @injectIntl
 class TimelineQueueButtonHeader extends React.PureComponent {
@@ -27,6 +28,7 @@ class TimelineQueueButtonHeader extends React.PureComponent {
     return (
       <div className={classes}>
         <a className='timeline-queue-header__btn' onClick={onClick}>
+          <SvgIcon src={require('@tabler/icons/icons/arrow-bar-to-up.svg')} />
           {(count > 0) && intl.formatMessage(message, { count })}
         </a>
       </div>