When an add-on update is found with the background update check, and a permission prompt is required (permissions changed), that prompt is only shown in the app menu notification, not through about:addons.

STR

1. Install an extension with an update that changes permissions (like https://github.com/firefox-devtools/Gecko-Profiler-Addon/blob/0c7eff42c96373a1247c82f54e6bc62ba1647f10/gecko_profiler.xpi)
2. Open a Browser Console and run the background update check
   • ChromeUtils.import("resource://gre/modules/AddonManager.jsm").AddonManagerPrivate.backgroundUpdateCheck()
3. Open about:addons and view available updates
4. Click Update Now for the add-on

Expected results: The permissions prompt is shown to confirm the permission changes.
Actual results: No permissions prompt is shown and the add-on is silently updated.

Note you'll need to disable automatic updates to be able to see the update in about:addons.

This patch prevents the addon-abuse-report-xulframe custom element from being defined
when AbuseReporter.openDialogDisabled is false (which is the default on all channels
starting from Firefox >= 73).

This change is also preventing the addon-abuse-report-xulframe custom element from
triggering an assertion failure in PresShell::ScrollContentIntoView, which seems to
be due to marionette calling browser.focus() while the custom element has just
injected the browser element that would contain the abuse report panel subframe.

This single-line patch is enough to prevent the assertion failure and still pass
all the existing tests. The addon-abuse-report-xulframe will be removed completely
as part of Bug 1614653.

Depends on D68805

https://hg.mozilla.org/mozilla-central/rev/bcda50c88646
https://hg.mozilla.org/mozilla-central/rev/ea9d07d6e6fb

Reproduced the issue using Firefox 68.0a1 (20190416220148) on Windows 10x64.
The issue is verified fixed with Firefox 77.0b7 (20200515125749) on Windows 10x64 and macOS 10.12. The update is performed only after clicking update on the permission prompt.