Function dispatch 

pub fn dispatch(
    data: EventData,
    ancestors_root_first: &[u64],
    bubbles: bool,
    invoke_host: impl FnMut(u64),
) -> EventData

Drive a full capture -> target -> bubble dispatch for data.

ancestors_root_first is the target’s ancestor chain packed-handle list, ordered root-first and EXCLUDING the target itself. Capture handlers on those ancestors fire top-down, then all handlers on the target, then (for a bubbling event) bubble handlers on the ancestors bottom-up. invoke_host runs a host-closure binding by token; native bindings are invoked directly. Returns the final EventData so the caller can read the default_prevented flag and apply (or skip) the default action.