Nested js_namespaces ignore the parent js_namespace

[RunDevelopment]

Describe the Bug

#[wasm_bindgen(js_namespace = ["a"])]
extern "C" {
    #[wasm_bindgen(js_namespace = ["b"])]
    fn my_function();
}

The above import generates the following JS glue code:

function __wbg_myfunction_8c7b624429f78550() {
    b.my_function();
};

Note the function is imported as b.my_function() and that js_namespace = ["a"] is ignored.

Expected Behavior

The parent js_namespace should not be ignored. The most sane behavior would probably be to import the function as a.b.my_function().