[mutter] screen: Remove stray assert

[Florian Müllner <fmuellner src gnome org>]

commit 80e595591803124c4e34a6ff8795a47fc6896d7f
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon Jun 26 17:56:36 2017 +0200

    screen: Remove stray assert
    
    When the number of (static) workspaces decreases, we relocate windows
    from extra workspaces before removing them. As removing a non-empty
    workspace is not allowed, we assert that it doesn't contain any windows
    before removing it.
    
    However that assert is
    
     - pointless, because meta_workspace_remove() already asserts that
       the workspace is empty
    
     - wrong, because even empty workspaces contain windows that are set
       to show on all workspaces
    
    Simply drop the assert to avoid a crash when trying to remove a workspace
    while on-all-workspaces windows are present.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=784223

 src/core/screen.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/src/core/screen.c b/src/core/screen.c
index d6b5eac..c6aa9e1 100644
--- a/src/core/screen.c
+++ b/src/core/screen.c
@@ -1260,7 +1260,6 @@ update_num_workspaces (MetaScreen *screen,
     {
       MetaWorkspace *w = l->data;
 
-      g_assert (w->windows == NULL);
       meta_workspace_remove (w);
     }