* We already make use of the closedId in RecentlyClosedTabsInView to re-open the tab via SS.undoCloseById so it made sense to do the same for forgetting a closed tab
* In the test setup, one of tabs is opened and closed in a different window. This gives us coverage both for the closed tab list rendering, as well as re-opening and forgeting tabs with different source windows
* Both the forget-by-closed-id methods match undoClosedById's behavior and throw if the closedId doesnt match a closed window or tab
Differential Revision: https://phabricator.services.mozilla.com/D184192
7bb84fd335