Use Class and Property Decorators (#3730)

ref https://tc39.github.io/proposal-decorators/

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

@@ -30,7 +30,9 @@ const mapStateToProps = state => ({
   columns: state.getIn(['settings', 'columns']),
 });
 
-class GettingStarted extends ImmutablePureComponent {
+@connect(mapStateToProps)
+@injectIntl
+export default class GettingStarted extends ImmutablePureComponent {
 
   static propTypes = {
     intl: PropTypes.object.isRequired,
@@ -105,5 +107,3 @@ class GettingStarted extends ImmutablePureComponent {
   }
 
 }
-
-export default connect(mapStateToProps)(injectIntl(GettingStarted));