Function host_load_imported_module 

pub(crate) fn host_load_imported_module(
    cx: &mut CurrentRealm<'_>,
    referrer: Handle<'_, *mut JSScript>,
    module_request: Handle<'_, *mut JSObject>,
    specifier: String,
    host_defined: Handle<'_, JSVal>,
    payload: Handle<'_, JSVal>,
)

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