Vendor dependencies

Let's see how I like this workflow.

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

@@ -0,0 +1,43 @@
+use wasm_bindgen::prelude::*;
+use wasm_bindgen_test::*;
+
+#[wasm_bindgen(module = "tests/wasm/char.js")]
+extern "C" {
+    fn js_identity(c: char) -> char;
+    fn js_works();
+}
+
+#[wasm_bindgen]
+pub fn rust_identity(c: char) -> char {
+    c
+}
+
+#[wasm_bindgen]
+pub fn rust_js_identity(c: char) -> char {
+    js_identity(c)
+}
+
+#[wasm_bindgen]
+pub fn letter() -> char {
+    'a'
+}
+
+#[wasm_bindgen]
+pub fn face() -> char {
+    '😀'
+}
+
+#[wasm_bindgen]
+pub fn rust_letter(a: char) {
+    assert_eq!(a, 'a');
+}
+
+#[wasm_bindgen]
+pub fn rust_face(p: char) {
+    assert_eq!(p, '😀');
+}
+
+#[wasm_bindgen_test]
+fn works() {
+    js_works();
+}