Vendor dependencies

Let's see how I like this workflow.

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

@@ -0,0 +1,15 @@
+use wasm_bindgen::prelude::*;
+use wasm_bindgen_test::*;
+
+#[wasm_bindgen(module = "tests/wasm/arg_names.js")]
+extern "C" {
+    fn js_arg_names();
+}
+
+#[wasm_bindgen]
+pub fn fn_with_many_args(_a: i32, _b: i32, _c: i32, _d: i32) {}
+
+#[wasm_bindgen_test]
+fn rust_arg_names() {
+    js_arg_names();
+}