Vendor dependencies

Let's see how I like this workflow.

vendor/wasm-bindgen/tests/wasm/jscast.js

@@ -0,0 +1,28 @@
+class JsCast1 {
+  constructor() {
+    this.val = 1;
+  }
+  myval() { return this.val; }
+}
+
+class JsCast2 {
+}
+
+class JsCast3 extends JsCast1 {
+  constructor() {
+    super();
+    this.val = 3;
+  }
+}
+
+class JsCast4 extends JsCast3 {
+  constructor() {
+    super();
+    this.val = 4;
+  }
+}
+
+exports.JsCast1 = JsCast1;
+exports.JsCast2 = JsCast2;
+exports.JsCast3 = JsCast3;
+exports.JsCast4 = JsCast4;