They showed Safari using the bar for various general browser functionality, e.g. back button and tab switcher, so that would require adding a toggle to switch f

They showed Safari using the bar for various general browser functionality, e.g. back button and tab switcher, so that would require adding a toggle to switch from that UI to the one the webpage has defined. I think Apple is going to use this to differentiate its native app offerings from competing web apps, particularly Google's web apps, so I doubt they put much effort into that.