Fix CVE-2017-8288:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-8288
http://seclists.org/oss-sec/2017/q2/136

Patch copied from upstream source repository:

https://git.gnome.org/browse/gnome-shell/commit/?id=ff425d1db7082e2755d2a405af53861552acf2a1

From ff425d1db7082e2755d2a405af53861552acf2a1 Mon Sep 17 00:00:00 2001
From: Emilio Pozuelo Monfort <pochu27@gmail.com>
Date: Tue, 25 Apr 2017 17:27:42 +0200
Subject: extensionSystem: handle reloading broken extensions

Some extensions out there may fail to reload. When that happens,
we need to catch any exceptions so that we don't leave things in
a broken state that could lead to leaving extensions enabled in
the screen shield.

https://bugzilla.gnome.org/show_bug.cgi?id=781728
---
 js/ui/extensionSystem.js | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/js/ui/extensionSystem.js b/js/ui/extensionSystem.js
index a4dc29e..fc352b8 100644
--- a/js/ui/extensionSystem.js
+++ b/js/ui/extensionSystem.js
@@ -282,12 +282,20 @@ function _onVersionValidationChanged() {
     // temporarily disable them all
     enabledExtensions = [];
     for (let uuid in ExtensionUtils.extensions)
-        reloadExtension(ExtensionUtils.extensions[uuid]);
+        try {
+            reloadExtension(ExtensionUtils.extensions[uuid]);
+        } catch(e) {
+            logExtensionError(uuid, e);
+        }
     enabledExtensions = getEnabledExtensions();
 
     if (Main.sessionMode.allowExtensions) {
         enabledExtensions.forEach(function(uuid) {
-            enableExtension(uuid);
+            try {
+                enableExtension(uuid);
+            } catch(e) {
+                logExtensionError(uuid, e);
+            }
         });
     }
 }
-- 
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