Remove unused variables (#3906)

app/javascript/mastodon/features/ui/components/boost_modal.js

@@ -2,7 +2,6 @@ import React from 'react';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import PropTypes from 'prop-types';
 import { defineMessages, injectIntl, FormattedMessage } from 'react-intl';
-import IconButton from '../../../components/icon_button';
 import Button from '../../../components/button';
 import StatusContent from '../../../components/status_content';
 import Avatar from '../../../components/avatar';
@@ -49,7 +48,7 @@ class BoostModal extends ImmutablePureComponent {
   }
 
   render () {
-    const { status, intl, onClose } = this.props;
+    const { status, intl } = this.props;
 
     return (
       <div className='modal-root__modal boost-modal'>