[gnome-sdk-images/gnome-3-24] Upgrade to WebKitGTK+ 2.20.4

[Michael Catanzaro <mcatanzaro src gnome org>]

commit ed697e2892b59d2e74b73797254cd53f601ee93f
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Mon Aug 6 08:42:57 2018 -0500

    Upgrade to WebKitGTK+ 2.20.4

 org.gnome.Sdk.json.in | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/org.gnome.Sdk.json.in b/org.gnome.Sdk.json.in
index 725e57e..22c7c43 100644
--- a/org.gnome.Sdk.json.in
+++ b/org.gnome.Sdk.json.in
@@ -609,8 +609,8 @@
             "sources": [
                 {
                     "type": "archive",
-                    "url": "https://webkitgtk.org/releases/webkitgtk-2.20.3.tar.xz";,
-                    "sha256": "579b307d78fa16a73f112790178022166d7ad17d4147492ced9b9fba48f20dd8"
+                    "url": "https://webkitgtk.org/releases/webkitgtk-2.20.4.tar.xz";,
+                    "sha256": "cc7dd15505c4f8a75d96deae148a82d7cc9034c7f3cc8a1fe4f969dddd92ae32"
                 },
                 {
                     "type": "patch",