[gnome-contacts] Window: use flag operations in window_state_event()

[Niels De Graef <nielsdg src gnome org>]

commit 3b8a1431d2ce24950b8be6d2b5b5514ab29c9577
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Sat Feb 24 17:21:03 2018 +0100

    Window: use flag operations in window_state_event()

 src/contacts-window.vala | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)
---
diff --git a/src/contacts-window.vala b/src/contacts-window.vala
index 1f493df..a626a07 100644
--- a/src/contacts-window.vala
+++ b/src/contacts-window.vala
@@ -112,13 +112,10 @@ public class Contacts.Window : Gtk.ApplicationWindow {
   }
 
   public override bool window_state_event (Gdk.EventWindowState event) {
-    if ((event.new_window_state & Gdk.WindowState.WITHDRAWN) == 0) {
-      bool maximized = (
-        (event.new_window_state & Gdk.WindowState.MAXIMIZED) != 0
-      );
-      if (this.window_maximized != maximized) {
+    if (!(Gdk.WindowState.WITHDRAWN in event.new_window_state)) {
+      bool maximized = (Gdk.WindowState.MAXIMIZED in event.new_window_state);
+      if (this.window_maximized != maximized)
         this.window_maximized = maximized;
-      }
     }
     return base.window_state_event (event);
   }