[gtk+] Revert "wayland: require WAYLAND_DISPLAY be set to open wayland display"

[Ray Strode <halfline src gnome org>]

commit 83c25169e8571a1c9f9009f34ca4bb5ca7f4e291
Author: Ray Strode <rstrode redhat com>
Date:   Fri Aug 14 11:24:44 2015 -0400

    Revert "wayland: require WAYLAND_DISPLAY be set to open wayland display"
    
    This reverts commit 35489f5d31b20a390b45803d760f965391d0b57f.
    
    It snuck in when i was trying to push
    
    commit f4d2022d46e16e1fdec8ca9b107a9870155832bf

 gdk/wayland/gdkdisplay-wayland.c |    5 +----
 1 files changed, 1 insertions(+), 4 deletions(-)
---
diff --git a/gdk/wayland/gdkdisplay-wayland.c b/gdk/wayland/gdkdisplay-wayland.c
index 7b8b0ee..32a0583 100644
--- a/gdk/wayland/gdkdisplay-wayland.c
+++ b/gdk/wayland/gdkdisplay-wayland.c
@@ -431,16 +431,13 @@ _gdk_wayland_display_open (const gchar *display_name)
 
   GDK_NOTE (MISC, g_message ("opening display %s", display_name ? display_name : ""));
 
-  /* If these variables are unset then wayland initialisation will surely
+  /* If this variable is unset then wayland initialisation will surely
    * fail, logging a fatal error in the process.  Save ourselves from
    * that.
    */
   if (g_getenv ("XDG_RUNTIME_DIR") == NULL)
     return NULL;
 
-  if (g_getenv ("WAYLAND_DISPLAY") == NULL)
-    return NULL;
-
   wl_log_set_handler_client (log_handler);
 
   wl_display = wl_display_connect (display_name);