Upgrade Babel to version 7.0.0 (#5925)

app/javascript/mastodon/features/ui/index.js

@@ -187,10 +187,10 @@ class SwitchingColumnsArea extends React.PureComponent {
 
 }
 
-@connect(mapStateToProps)
+export default @connect(mapStateToProps)
 @injectIntl
 @withRouter
-export default class UI extends React.PureComponent {
+class UI extends React.PureComponent {
 
   static contextTypes = {
     router: PropTypes.object.isRequired,