Seen in browser-chrome test logs:
Created attachment 544619 [details] [diff] [review]
I'd like to have checked in ThumbnailStorage.loadThumbnail() whether the given tab is still linked to a TabItem before executing the callback but that's not possible as the tab might have been re-used be SS/SR in the meantime. So we need to check if the TabItem is still linked to a tab in TabItem._reconnect();
Comment on attachment 544619 [details] [diff] [review]
I don't think there's a point in checking tabData before self.tab.
*** Bug 670852 has been marked as a duplicate of this bug. ***