Move the js module to a js_sys crate (#512)

* Move the `js` module to a `js_sys` crate

* Update js-sys tests to pass again

* Update binding_to_unimplemented_apis_doesnt_break_everything

Remove its dependency on the `js` module

* Update metadata for js-sys

* Fix the `closures` example

crates/js-sys/tests/all/ArrayIterator.rs

@@ -0,0 +1,128 @@
+#![allow(non_snake_case)]
+
+use project;
+
+#[test]
+fn keys() {
+    project()
+        .file(
+            "src/lib.rs",
+            r#"
+            #![feature(use_extern_macros)]
+
+            extern crate wasm_bindgen;
+            extern crate js_sys;
+            use wasm_bindgen::prelude::*;
+
+            #[wasm_bindgen]
+            pub fn get_keys(this: &js_sys::Array) -> js_sys::ArrayIterator {
+                this.keys()
+            }
+
+        "#,
+        )
+        .file(
+            "test.js",
+            r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                let numbers = [8, 5, 4, 3, 1, 2];
+                let iterator = numbers.keys();
+                let wasmIterator = wasm.get_keys(numbers);
+
+                assert.equal(iterator.toString(), wasmIterator.toString());
+                assert.equal(Array.from(iterator)[0], Array.from(wasmIterator)[0]);
+            }
+        "#,
+        )
+        .test()
+}
+
+#[test]
+fn entries() {
+    project()
+        .file(
+            "src/lib.rs",
+            r#"
+            #![feature(use_extern_macros)]
+
+            extern crate wasm_bindgen;
+            extern crate js_sys;
+            use wasm_bindgen::prelude::*;
+
+            #[wasm_bindgen]
+            pub fn get_entries(this: &js_sys::Array) -> js_sys::ArrayIterator {
+                this.entries()
+            }
+
+        "#,
+        )
+        .file(
+            "test.js",
+            r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                let numbers = [8, 5, 4, 3, 1, 2];
+                let iterator = numbers.entries();
+                let wasmIterator = wasm.get_entries(numbers);
+                let jsItem = iterator.next();
+                let wasmItem = wasmIterator.next();
+
+                assert.equal(iterator.toString(), wasmIterator.toString());
+                assert.equal(jsItem.value[1], wasmItem.value[1]);
+            }
+        "#,
+        )
+        .test()
+}
+
+#[test]
+fn values() {
+    let mut project = project();
+    project.file(
+            "src/lib.rs",
+            r#"
+            #![feature(use_extern_macros)]
+
+            extern crate wasm_bindgen;
+            extern crate js_sys;
+            use wasm_bindgen::prelude::*;
+
+            #[wasm_bindgen]
+            pub fn get_values(this: &js_sys::Array) -> js_sys::ArrayIterator {
+                this.values()
+            }
+        "#,
+        )
+        .file(
+            "test.js",
+            r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                if (typeof Array.prototype.values !== "function") {
+                    return;
+                }
+
+                let numbers = [8, 3, 2];
+                let wasmIterator = wasm.get_values(numbers);
+
+                assert.equal(wasmIterator.next().value, 8);
+                assert.equal(wasmIterator.next().value, 3);
+                assert.equal(wasmIterator.next().value, 2);
+                assert.ok(wasmIterator.next().done);
+            }
+        "#,
+        );
+
+    let mut headless = project.clone();
+    headless.headless(true);
+
+    project.test();
+    headless.test();
+}