[gtk+] Use a variable consistently

[Matthias Clasen <matthiasc src gnome org>]

commit e502702dd405466215e24fc2c242e389bf07085f
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Apr 30 23:15:20 2016 -0400

    Use a variable consistently

 gdk/gdkwindow.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/gdk/gdkwindow.c b/gdk/gdkwindow.c
index 8e4fd85..210cca3 100644
--- a/gdk/gdkwindow.c
+++ b/gdk/gdkwindow.c
@@ -3702,13 +3702,15 @@ gdk_window_process_updates_internal (GdkWindow *window)
 
          expose_region = cairo_region_copy (window->active_update_area);
 
+         impl_class = GDK_WINDOW_IMPL_GET_CLASS (window->impl);
+
           /* Sometimes we can't just paint only the new area, as the windowing system
            * requires more to be repainted. For instance, with OpenGL you typically
            * repaint all of each frame each time and then swap the buffer, although
            * there are extensions that allow us to reuse part of an old frame.
            */
-          if (GDK_WINDOW_IMPL_GET_CLASS (window->impl)->invalidate_for_new_frame)
-            GDK_WINDOW_IMPL_GET_CLASS (window->impl)->invalidate_for_new_frame (window, expose_region);
+          if (impl_class->invalidate_for_new_frame)
+            impl_class->invalidate_for_new_frame (window, expose_region);
 
          /* Clip to part visible in impl window */
          cairo_region_intersect (expose_region, window->clip_region);
@@ -3725,8 +3727,6 @@ gdk_window_process_updates_internal (GdkWindow *window)
              g_usleep (70000);
            }
 
-         impl_class = GDK_WINDOW_IMPL_GET_CLASS (window->impl);
-
           if (impl_class->queue_antiexpose)
             impl_class->queue_antiexpose (window, expose_region);