pub unsafe extern "C" fn webkit_web_view_call_async_javascript_function(
    web_view: *mut WebKitWebView,
    body: *const c_char,
    length: ssize_t,
    arguments: *mut GVariant,
    world_name: *const c_char,
    source_uri: *const c_char,
    cancellable: *mut GCancellable,
    callback: GAsyncReadyCallback,
    user_data: gpointer
)
Available on crate feature v2_40 only.