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/DataView.rs

@@ -0,0 +1,56 @@
+#![allow(non_snake_case)]
+
+use super::project;
+
+#[test]
+fn test() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(use_extern_macros)]
+
+            extern crate wasm_bindgen;
+            extern crate js_sys;
+            use wasm_bindgen::prelude::*;
+            use js_sys::{ArrayBuffer, DataView};
+
+            #[wasm_bindgen]
+            pub fn test_data_view(buffer: &ArrayBuffer, offset: usize, len: usize) {
+                let v = DataView::new(buffer, offset, len);
+                assert_eq!(v.byte_offset(), offset);
+                assert_eq!(v.byte_length(), len);
+                assert_eq!(v.get_int8(0), 2);
+                assert_eq!(v.get_uint8(0), 2);
+                
+                v.set_int8(0, 42);
+                assert_eq!(v.get_int8(0), 42);
+                v.set_uint8(0, 255);
+                assert_eq!(v.get_uint8(0), 255);
+                v.set_int16(0, 32767);
+                assert_eq!(v.get_int16(0), 32767);
+                v.set_uint16(0, 65535);
+                assert_eq!(v.get_uint16(0), 65535);
+                v.set_int32(0, 123456789);
+                assert_eq!(v.get_int32(0), 123456789);
+                v.set_uint32(0, 3_123_456_789);
+                assert_eq!(v.get_uint32(0), 3_123_456_789);
+                v.set_float32(0, 100.123);
+                assert_eq!(v.get_float32(0), 100.123);
+                v.set_float64(0, 123456789.123456);
+                assert_eq!(v.get_float64(0), 123456789.123456);
+
+                v.set_int8(0, 42);
+            }
+        "#)
+        .file("test.js", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                const bytes = new Int8Array(10);
+                bytes[2] = 2;
+                wasm.test_data_view(bytes.buffer, 2, 8);
+                assert.equal(bytes[2], 42);
+            }
+        "#)
+        .test()
+}