Vendor dependencies

Let's see how I like this workflow.

vendor/wasm-bindgen-macro/ui-tests/invalid-enums.stderr

@@ -0,0 +1,23 @@
+error: cannot export empty enums to JS
+ --> $DIR/invalid-enums.rs:4:1
+  |
+4 | enum A {}
+  | ^^^^^^^^^
+
+error: only C-Style enums allowed with #[wasm_bindgen]
+ --> $DIR/invalid-enums.rs:8:6
+  |
+8 |     D(u32),
+  |      ^^^^^
+
+error: enums with #[wasm_bindgen] may only have number literal values
+  --> $DIR/invalid-enums.rs:13:9
+   |
+13 |     X = 1 + 3,
+   |         ^^^^^
+
+error: enums with #[wasm_bindgen] can only support numbers that can be represented as u32
+  --> $DIR/invalid-enums.rs:18:9
+   |
+18 |     X = 4294967296,
+   |         ^^^^^^^^^^