Vendor dependencies

Let's see how I like this workflow.

vendor/js-sys/tests/wasm/UriError.rs

@@ -0,0 +1,17 @@
+use js_sys::*;
+use wasm_bindgen::JsCast;
+use wasm_bindgen::JsValue;
+use wasm_bindgen_test::*;
+
+#[wasm_bindgen_test]
+fn uri_error() {
+    let error = UriError::new("msg");
+    assert!(error.is_instance_of::<UriError>());
+    assert!(error.is_instance_of::<Error>());
+    assert!(error.is_instance_of::<Object>());
+    let _: &Error = error.as_ref();
+    let _: &Object = error.as_ref();
+
+    let base: &Error = error.as_ref();
+    assert_eq!(JsValue::from(base.message()), "msg");
+}