Function get_type_and_value_from_message

pub(crate) unsafe fn get_type_and_value_from_message(
    cx: JSContext,
    data: HandleValue<'_>,
    value: MutableHandleValue<'_>,
    can_gc: CanGc,
) -> DOMString

The initial steps for the message handler for both readable and writable cross realm transforms. https://streams.spec.whatwg.org/#abstract-opdef-setupcrossrealmtransformreadable https://streams.spec.whatwg.org/#abstract-opdef-setupcrossrealmtransformwritable