[gnome-sdk-images] webkit: bump to 2.15.4

[Christian Hergert <chergert src gnome org>]

commit 1045b2d0a0db92da0c3b1277d279ec048fbec875
Author: Christian Hergert <chergert redhat com>
Date:   Fri Feb 3 01:05:37 2017 -0800

    webkit: bump to 2.15.4
    
    This is the most recent devel snapshot.

 org.gnome.Sdk.json.in |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/org.gnome.Sdk.json.in b/org.gnome.Sdk.json.in
index 0ff6970..8b706d3 100644
--- a/org.gnome.Sdk.json.in
+++ b/org.gnome.Sdk.json.in
@@ -722,8 +722,8 @@
             "sources": [
                 {
                     "type": "archive",
-                    "url": "https://www.webkitgtk.org/releases/webkitgtk-2.15.2.tar.xz";,
-                    "sha256": "756f14ad2ca84e25dc245f2b736ab31de58d1eb66fef76e75a1985179072471f"
+                    "url": "https://www.webkitgtk.org/releases/webkitgtk-2.15.4.tar.xz";,
+                    "sha256": "b5548a8a0a9e3133bd5a27f4fd0307f58871409134c308a9f09db8baa83a8bf4"
                 },
                 {
                     "type": "patch",