[gtk] widget: Fail if matrix not invertible

[Benjamin Otte <otte src gnome org>]

commit 8fbfa955de38d2c59a460d5b9e1c62b622f6b50d
Author: Benjamin Otte <otte redhat com>
Date:   Wed Feb 20 04:05:37 2019 +0100

    widget: Fail if matrix not invertible

 gtk/gtkwidget.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index d4a8284ae4..c3395494ad 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -11292,7 +11292,8 @@ gtk_widget_compute_transform (GtkWidget         *widget,
 
       graphene_matrix_multiply (&inverse, &priv->transform, &inverse);
     }
-  graphene_matrix_inverse (&inverse, &inverse);
+  if (!graphene_matrix_inverse (&inverse, &inverse))
+    return FALSE;
 
   graphene_matrix_multiply (&transform, &inverse, out_transform);