* Add a browser.sessionstore.closedTabsFromClosedWindows pref and consult it when building recently-closed tab lists in firefoxview-next
* Add a _resolveClosedDataSource to SessionStore which allows us to find the window state and _closedTabs given a DOMWindow, a window closedId, or a window session store Id.
* Carry window closedId and source window Id into tab items when building recently-closed tab lists in firefoxview-next. This gives us the necessary context when we need to undoClose or forget a tab item in the list.
* Add a getClosed TabCount and TabData for Closed Windows method to SessionStore
* Modify undoCloseTab and forgetClosedTab to accept source params we can resolve to window state data using _resolveClosedDataSource
Differential Revision: https://phabricator.services.mozilla.com/D185108
f078d2dc51