* Fix various z-index/paint order issues by making the urlbar a popover - which moves the open
urlbar to the top layer, outside the toolbox
* Adjust the urlbar position when the autohide menubar shows and hides
* Temporarily disable the browser_urlbar_keyed_search.js which needs revisiting to measure reflows under regular, non-test-specific conditions
Combines work from nsharpley and sfoster on top of emilio's original popover patch
Differential Revision: https://phabricator.services.mozilla.com/D224201
4ea54f6e0f