[gtk+] cssselector: Don't invoke undefined behavior

[Matthias Clasen <matthiasc src gnome org>]

commit 6108c646c57c6c489225f5e5e6484ac282c07bdf
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Feb 26 14:48:21 2016 -0500

    cssselector: Don't invoke undefined behavior
    
    Avoid undefined behavior in the calculation of some
    hash values. Found by gcc's undefined behavior sanitizer.

 gtk/gtkcssselector.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkcssselector.c b/gtk/gtkcssselector.c
index f0e91b2..9309de5 100644
--- a/gtk/gtkcssselector.c
+++ b/gtk/gtkcssselector.c
@@ -842,7 +842,7 @@ match_pseudoclass_position (const GtkCssSelector *selector,
 static guint
 hash_pseudoclass_position (const GtkCssSelector *a)
 {
-  return (((a->position.type << POSITION_NUMBER_BITS) | a->position.a) << POSITION_NUMBER_BITS) | 
a->position.b;
+  return (guint)(((((gulong)a->position.type) << POSITION_NUMBER_BITS) | a->position.a) << 
POSITION_NUMBER_BITS) | a->position.b;
 }
 
 static int