Fix deprecated use of createBrowserHistory

app/javascript/core/public.js

@@ -1,6 +1,5 @@
 //  This file will be loaded on public pages, regardless of theme.
 
-import createHistory from 'history/createBrowserHistory';
 import ready from '../mastodon/ready';
 
 const { delegate } = require('@rails/ujs');

app/javascript/flavours/glitch/components/modal_root.js

@@ -1,7 +1,7 @@
 import React from 'react';
 import PropTypes from 'prop-types';
 import 'wicg-inert';
-import createHistory from 'history/createBrowserHistory';
+import { createBrowserHistory } from 'history';
 
 export default class ModalRoot extends React.PureComponent {
   static contextTypes = {
@@ -51,7 +51,7 @@ export default class ModalRoot extends React.PureComponent {
   componentDidMount () {
     window.addEventListener('keyup', this.handleKeyUp, false);
     window.addEventListener('keydown', this.handleKeyDown, false);
-    this.history = this.context.router ? this.context.router.history : createHistory();
+    this.history = this.context.router ? this.context.router.history : createBrowserHistory();
   }
 
   componentWillReceiveProps (nextProps) {