Vendor dependencies

Let's see how I like this workflow.

vendor/js-sys/tests/headless.rs

@@ -0,0 +1,47 @@
+#![cfg(target_arch = "wasm32")]
+
+extern crate js_sys;
+extern crate wasm_bindgen;
+extern crate wasm_bindgen_test;
+
+use js_sys::Array;
+use wasm_bindgen::prelude::*;
+use wasm_bindgen_test::*;
+
+wasm_bindgen_test_configure!(run_in_browser);
+
+#[wasm_bindgen(module = "/tests/headless.js")]
+extern "C" {
+    fn is_array_values_supported() -> bool;
+}
+
+#[wasm_bindgen]
+extern "C" {
+    type ValuesIterator;
+    #[wasm_bindgen(method, structural)]
+    fn next(this: &ValuesIterator) -> IterNext;
+
+    type IterNext;
+
+    #[wasm_bindgen(method, getter, structural)]
+    fn value(this: &IterNext) -> JsValue;
+    #[wasm_bindgen(method, getter, structural)]
+    fn done(this: &IterNext) -> bool;
+}
+
+#[wasm_bindgen_test]
+fn array_iterator_values() {
+    if !is_array_values_supported() {
+        return;
+    }
+    let array = Array::new();
+    array.push(&8.into());
+    array.push(&3.into());
+    array.push(&2.into());
+    let iter = ValuesIterator::from(JsValue::from(array.values()));
+
+    assert_eq!(iter.next().value(), 8);
+    assert_eq!(iter.next().value(), 3);
+    assert_eq!(iter.next().value(), 2);
+    assert!(iter.next().done());
+}