[gtk+/gtk-3-18] stylecontext: Make sure style is valid when looking up style properties

[Matthias Clasen <matthiasc src gnome org>]

commit 83427240220c0fb412140a169560516a1edcc250
Author: Benjamin Otte <otte redhat com>
Date:   Sat Oct 10 23:21:45 2015 +0200

    stylecontext: Make sure style is valid when looking up style properties
    
    Otherwise, the validation may happen vey automatically some time during
    the style property and that will most likely cause a crash.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=756338

 gtk/gtkstylecontext.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkstylecontext.c b/gtk/gtkstylecontext.c
index 9176c02..f8822c1 100644
--- a/gtk/gtkstylecontext.c
+++ b/gtk/gtkstylecontext.c
@@ -1621,6 +1621,9 @@ _gtk_style_context_peek_style_property (GtkStyleContext *context,
 
   priv = context->priv;
 
+  /* ensure the style cache is valid by forcing a validation */
+  gtk_style_context_lookup_style (context);
+
   key.widget_type = widget_type;
   key.pspec = pspec;