This patch fixes a number of issues that clear up a few different
intermittents in browser_tab_preview.js.
1. In browser_tab_groups_tab_interactions_telemetry.js, a call to "close
duplicate tabs" would automatically open the confirmation hint panel.
If not manually closed, it seems to persist in a half-way open state
where the `animating` attribute is always `true`. This is now fixed.
2. There is a test somewhere that seems to apply the
`sidebar.verticalTabs` pref and doesn't turn it off. I would like to
figure out which test is causing this, but as a last defence I have
made sure this is always properly set within this test suite.
3. Some tests check that THP is disabled if another panel is open. These
used to work by opening the `appMenu-popup` menu (the hamburger menu
in the top right of the browser). The problem with this approach is
that this panel (and basically every other panel) are very complex
and are prone to change. This was causing an intermittent failure
where attempting to close this panel threw an error in console that
seemed to be specifically related to this panel. I fixed this by
creating a fake minimal panel that is guaranteed to not change as
application code changes. (I borrowed this technique from
https://searchfox.org/mozilla-central/source/browser/base/content/test/popupNotifications/browser_popupNotification_queue.js).
4. There is a suite of tests that checks that THP is disabled in the
event that a drag operation is performed. The problem is that
dragging a tab by 100px sometimes detaches the tab and creates a new
window, breaking the test run. Reducing the drag amount seems to fix
this.
5. As a last line of defence, I have added a state reset function at the
start of each test to ensure that all panels are closed and that the
mouse is not hovering over the tab strip. (The latter was being done at
the end of some tests already, but this makes sure it is consistently
applied everywhere.)
Closes bug1898099, bug1905944, bug1933597.
Differential Revision: https://phabricator.services.mozilla.com/D258976
520c64e4d9