Get NoScript using packages from experimental

The version currently in unstable is old and breaks at least YouTube and
Hotmail. This is also closer to what TBB currently ships.

config/chroot_apt/preferences

@@ -307,7 +307,7 @@ Pin: release o=Debian,a=unstable
 Pin-Priority: 999
 
 Package: xul-ext-noscript
-Pin: release o=Debian,a=unstable
+Pin: release o=Debian,a=experimental
 Pin-Priority: 999
 
 Package: xul-ext-torbutton