[gtk+] cssstyle: fix a compiler warning

[Cosimo Cecchi <cosimoc src gnome org>]

commit a009a50239520f1227721e3b9399adbecda04784
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Sun Jan 3 17:20:06 2016 -0800

    cssstyle: fix a compiler warning

 gtk/gtkcssstyle.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkcssstyle.c b/gtk/gtkcssstyle.c
index 794a20a..d801c64 100644
--- a/gtk/gtkcssstyle.c
+++ b/gtk/gtkcssstyle.c
@@ -137,8 +137,8 @@ gtk_css_style_print (GtkCssStyle *style,
   guint i;
   gboolean retval = FALSE;
 
-  g_return_if_fail (GTK_IS_CSS_STYLE (style));
-  g_return_if_fail (string != NULL);
+  g_return_val_if_fail (GTK_IS_CSS_STYLE (style), FALSE);
+  g_return_val_if_fail (string != NULL, FALSE);
 
   for (i = 0; i < _gtk_css_style_property_get_n_properties (); i++)
     {