[Glitch] Remove legacy decorators syntax

Port d1b057a0ac to glitch-soc

app/javascript/flavours/glitch/features/ui/components/header.jsx

@@ -23,8 +23,6 @@ const mapDispatchToProps = (dispatch) => ({
   },
 });
 
-export default @withRouter
-@connect(null, mapDispatchToProps)
 class Header extends React.PureComponent {
 
   static contextTypes = {
@@ -86,3 +84,5 @@ class Header extends React.PureComponent {
   }
 
 }
+
+export default withRouter(connect(null, mapDispatchToProps)(Header));