[gtk+/gtk-3-18] gdkpixbuf-drawable: reinstate accidentally removed line

[Matthias Clasen <matthiasc src gnome org>]

commit bfdff24b1023e8dd2db23941f3d8caf77a0a33d9
Author: Lars Uebernickel <lars uebernickel canonical com>
Date:   Tue Oct 27 13:38:14 2015 +0100

    gdkpixbuf-drawable: reinstate accidentally removed line

 gdk/gdkpixbuf-drawable.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gdk/gdkpixbuf-drawable.c b/gdk/gdkpixbuf-drawable.c
index 2e3de8c..0647e3c 100644
--- a/gdk/gdkpixbuf-drawable.c
+++ b/gdk/gdkpixbuf-drawable.c
@@ -119,6 +119,7 @@ gdk_cairo_format_for_content (cairo_content_t content)
     {
     case CAIRO_CONTENT_COLOR:
       return CAIRO_FORMAT_RGB24;
+    case CAIRO_CONTENT_ALPHA:
       return CAIRO_FORMAT_A8;
     case CAIRO_CONTENT_COLOR_ALPHA:
     default: