> "scroll to top" by tapping the title bar is completely broken

This is because the scrolling is in a container rather than the body. It's a tough problem on many mobile pages using sliding drawers for example, which rely on overflow based scrolling. There's no event, that I'm aware of, for a web app to listen for for tapping that UI element on iOS.

Ultimately, it's a non-standard convenience introduced on iOS only. Maybe someone else here has solved this :)