Permission exception when Gnom ATK wrapper is installed

[hrj]

In Ubuntu 18.04, the openjdk-8 package depends on libatk-wrapper-java. This package adds a new extension library into the JDK directory, and this extension causes the stack trace to change whenever AWT is involved:

 	at java.security.AccessController.doPrivileged(Native Method)
 	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
 	at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
+	at org.GNOME.Accessibility.AtkWrapper$6.dispatchEvent(AtkWrapper.java:715)
 	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
 	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
 	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)

Because of this, gngr fails to load all pages, including about:welcome.

The user can disable the extension by this command line option: -Djavax.accessibility.assistive_technologies=" "

Fixing this for everyone will require more permissions to be given to the extension libraries.

This issue highlights the flakiness of the current approach. In future, we will need to be very permissive with the extension libraries to pre-empt such failures and / or use a better design around modules.