The `PanelMultiView.showSubView()` method needed to be made a bit more robust for titles set by DOM localization rather than directly. The following messages are dropped during the migration, as they are unused: - contentBlocking.trackersView.blocked.label - contentBlocking.cookiesView.firstParty.empty.label - contentBlocking.cookiesView.trackers.empty.label - contentBlocking.cookiesView.thirdParty.empty.label - contentBlocking.fingerprintersView.blocked.label - contentBlocking.cryptominersView.blocked.label Differential Revision: https://phabricator.services.mozilla.com/D178829