Vendor dependencies

Let's see how I like this workflow.

vendor/wasm-bindgen/guide/src/examples/import-js.md

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+# Importing non-browser JS
+
+[View full source code][code] or [view the compiled example online][online]
+
+[online]: https://rustwasm.github.io/wasm-bindgen/exbuild/import_js/
+[code]: https://github.com/rustwasm/wasm-bindgen/tree/master/examples/import_js
+
+The `#[wasm_bindgen]` attribute can be used on `extern "C" { .. }` blocks to import
+functionality from JS. This is how the `js-sys` and the `web-sys` crates are
+built, but you can also use it in your own crate!
+
+For example if you're working with this JS file:
+
+```js
+// defined-in-js.js
+{{#include ../../../examples/import_js/crate/defined-in-js.js}}
+```
+
+you can use it in Rust with:
+
+```rust
+{{#include ../../../examples/import_js/crate/src/lib.rs}}
+```
+
+You can also [explore the full list of ways to configure imports][attr]
+
+[attr]: ../reference/attributes/on-js-imports/index.html