Bug 579540 - Intermittent timeout in browser/base/content/test/browser_bug553455.js, followed by various failures about number of installed extensions or notifications, probably depending on when it timed out; r=gavin a=orange-fix

Try to increase the timeout to twice its previous amount in the hopes that it fixes the intermittent timeout in this test.

browser/base/content/test/browser_bug553455.js

@@ -597,7 +597,7 @@ var XPInstallObserver = {
 };
 
 function test() {
-  requestLongerTimeout(2);
+  requestLongerTimeout(4);
   waitForExplicitFinish();
 
   Services.prefs.setBoolPref("extensions.logging.enabled", true);