Vendor things

third-party/vendor/wasm-bindgen-macro/README.md

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+# `wasm-bindgen-macro`
+
+Implementation of the `#[wasm_bindgen]` attribute. See the `wasm-bindgen`
+documentation for more information about what this macro does.
+
+## Testing
+
+Testing of this macro is done through "ui tests" in the `ui-tests` subdirectory
+of this crate. Each Rust file in this folder is compiled with the `wasm_bindgen`
+crate, and the `*.stderr` file sitting next to it is the asserted output of the
+compiler. If the output matches, the test passes, and if the output doesn't
+match the test fails. Note that it is also considered a failure if a test
+actually compiles successfully.
+
+To add a test:
+
+* Create `ui-tests/my-awesome-test.rs`
+* Write an invalid `#[wasm_bindgen]` invocation, testing the error you're
+  generating
+* Execute `cargo test -p ui-tests`, the test will fail
+* From within the `ui-tests` folder, execute `./update-all-references.sh`. This
+  should create a `my-awesome-test.stderr` file.
+* Inspect `my-awesome-test.stderr` to make sure it looks ok
+* Rerun `cargo test -p ui-tests` and your tests should pass!
+
+Testing here is a work in progress, see
+[#601](https://github.com/rustwasm/wasm-bindgen/issues/601) for more
+information.