[gnome-sdk-images] Update WebKit to latest tarball

[Alexander Larsson <alexl src gnome org>]

commit 9bad46c00fbac3ff6e12dc4b514e505a5b3716a5
Author: Alexander Larsson <alexl redhat com>
Date:   Tue Aug 9 14:46:28 2016 +0200

    Update WebKit to latest tarball

 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 1b90613..2a27993 100644
--- a/org.gnome.Sdk.json.in
+++ b/org.gnome.Sdk.json.in
@@ -708,8 +708,8 @@
             "sources": [
                 {
                     "type": "archive",
-                    "url": "http://www.webkitgtk.org/releases/webkitgtk-2.12.1.tar.xz";,
-                    "sha256": "5b1a2d5227553f3cecbdb258c68b384f9235747b2c07c15afb555fe4fa6ae896"
+                    "url": "https://www.webkitgtk.org/releases/webkitgtk-2.13.4.tar.xz";,
+                    "sha256": "d044d656ed8c8ce7e64efa0eee7939f130d151c72612b51e4e002d9a4f3a3084"
                 },
                 {
                     "type": "patch",