Follow-up 6ec34a3de: Fix bug and exception in edit notice button

After 6ec34a3de the edit notice button was no longer hidden by
default if there were no notices. The alert icon was always
visible (when clicked it would show "0 notices").

In addition, on any page (except pages with edit notices) it
would throw a fatal exception at load time because method .hide()
doesn't exist.

As a result, current master shows an incomplete toolbar (e.g. not even
a Save button!)

Change-Id: Ib6e91c4756664c25fbb7403ef54b4fffcc0f9938
Merge "Follow-up 6ec34a3de: Fix bug and exception in edit notice button"