[mutter/wayland] wayland: Pull in a fix for a FIXME from Weston

[Jasper St. Pierre <jstpierre src gnome org>]

commit 5298cf0a3a5e42e1995f5a36a83e2d0a352a73f7
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Tue Mar 11 15:13:15 2014 -0400

    wayland: Pull in a fix for a FIXME from Weston

 src/wayland/meta-wayland-data-device.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/src/wayland/meta-wayland-data-device.c b/src/wayland/meta-wayland-data-device.c
index 11c329e..0785c6d 100644
--- a/src/wayland/meta-wayland-data-device.c
+++ b/src/wayland/meta-wayland-data-device.c
@@ -318,8 +318,12 @@ data_device_start_drag (struct wl_client *client,
 {
   MetaWaylandSeat *seat = wl_resource_get_user_data (resource);
   MetaWaylandDragGrab *drag_grab;
-  /* FIXME: Check that client has implicit grab on the origin
-   * surface that matches the given time. */
+
+  if ((seat->pointer.button_count == 0 ||
+       seat->pointer.grab_serial != serial ||
+       !seat->pointer.focus_surface ||
+       seat->pointer.focus_surface != wl_resource_get_user_data (origin_resource)))
+    return;
 
   /* FIXME: Check that the data source type array isn't empty. */