[gtk+/gtk-3-18] Avoid division by 0 in the border rendering code

[Matthias Clasen <matthiasc src gnome org>]

commit f7b0b523aca3f9048f27b280a95ab1434045ca18
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Jan 9 17:30:33 2016 -0500

    Avoid division by 0 in the border rendering code
    
    We skip sides with 0 border width in render_border, but when
    we collect sides with the same style, we may pass the 0 width
    down to render_frame_stroke anyway. So skip width 0 sides
    there as well.

 gtk/gtkrenderborder.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkrenderborder.c b/gtk/gtkrenderborder.c
index 49d9470..47973ad 100644
--- a/gtk/gtkrenderborder.c
+++ b/gtk/gtkrenderborder.c
@@ -518,11 +518,14 @@ render_frame_stroke (cairo_t       *cr,
                                border_width[GTK_CSS_BOTTOM],
                                border_width[GTK_CSS_LEFT]);
 
-      for (i = 0; i < 4; i++) 
+      for (i = 0; i < 4; i++)
         {
           if (hidden_side & (1 << i))
             continue;
 
+          if (border_width[i] == 0)
+            continue;
+
           cairo_save (cr);
 
           if (i == 0)