Vendor dependencies

Let's see how I like this workflow.

vendor/wasm-bindgen/tests/wasm/rethrow.rs

@@ -0,0 +1,28 @@
+use wasm_bindgen::prelude::*;
+use wasm_bindgen_test::*;
+
+#[wasm_bindgen(module = "tests/wasm/rethrow.js")]
+extern "C" {
+    fn call_throw_one();
+    fn call_ok();
+}
+
+#[wasm_bindgen_test]
+fn err_works() {
+    call_throw_one();
+}
+
+#[wasm_bindgen]
+pub fn throw_one() -> Result<u32, JsValue> {
+    Err(1.into())
+}
+
+#[wasm_bindgen_test]
+fn ok_works() {
+    call_ok();
+}
+
+#[wasm_bindgen]
+pub fn nothrow() -> Result<u32, JsValue> {
+    Ok(1)
+}