Function host_load_imported_module 

pub(crate) fn host_load_imported_module(
    cx: JSContext,
    referrer_module: Option<Rc<ModuleTree>>,
    referrer: HandleValue,
    specifier: String,
    load_state: Option<Rc<LoadState>>,
    payload: Payload,
)

https://html.spec.whatwg.org/multipage/#hostloadimportedmodule