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/Error.rs

@@ -0,0 +1,197 @@
+#![allow(non_snake_case)]
+
+use project;
+
+#[test]
+fn new() {
+    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::Error;
+
+            #[wasm_bindgen]
+            pub fn new_error(message: &js_sys::JsString) -> Error {
+                Error::new(message)
+            }
+        "#)
+        .file("test.js", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                const message = 'any error message';
+                const error = wasm.new_error(message);
+
+                assert.equal(error.message, message);
+            }
+        "#)
+        .test()
+}
+
+#[test]
+fn message() {
+    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::Error;
+
+            #[wasm_bindgen]
+            pub fn error_message(this: &Error) -> js_sys::JsString {
+                this.message()
+            }
+        "#)
+        .file("test.js", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                const message = 'any error message';
+                const error = new Error(message);
+
+                assert.equal(wasm.error_message(error), message);
+            }
+        "#)
+        .test()
+}
+
+#[test]
+fn set_message() {
+    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::Error;
+
+            #[wasm_bindgen]
+            pub fn error_set_message(this: &Error, message: &js_sys::JsString) {
+                this.set_message(message);
+            }
+        "#)
+        .file("test.js", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                const message = 'any error message';
+                const error = new Error();
+                wasm.error_set_message(error, message);
+
+                assert.equal(error.message, message);
+            }
+        "#)
+        .test()
+}
+
+#[test]
+fn name() {
+    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::Error;
+
+            #[wasm_bindgen]
+            pub fn error_name(this: &Error) -> js_sys::JsString {
+                this.name()
+            }
+        "#)
+        .file("test.js", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                const name = 'any error name';
+                const error = new Error();
+                error.name = name;
+
+                assert.equal(wasm.error_name(error), name);
+            }
+        "#)
+        .test()
+}
+
+#[test]
+fn set_name() {
+    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::Error;
+
+            #[wasm_bindgen]
+            pub fn error_set_name(this: &Error, name: &js_sys::JsString) {
+                this.set_name(name);
+            }
+        "#)
+        .file("test.js", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                const name = 'any error name';
+                const error = new Error();
+                wasm.error_set_name(error, name);
+
+                assert.equal(error.name, name);
+            }
+        "#)
+        .test()
+}
+
+#[test]
+fn to_string() {
+    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::Error;
+
+            #[wasm_bindgen]
+            pub fn error_to_string(this: &Error) -> js_sys::JsString {
+                this.to_string()
+            }
+        "#)
+        .file("test.js", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                const error = new Error('error message 1');
+
+                assert.equal(wasm.error_to_string(error), 'Error: error message 1');
+
+                error.name = undefined;
+                assert.equal(wasm.error_to_string(error), 'Error: error message 1');
+
+                error.name = 'error_name_1';
+                assert.equal(wasm.error_to_string(error), 'error_name_1: error message 1');
+
+                error.message = undefined;
+                assert.equal(wasm.error_to_string(error), 'error_name_1');
+
+                error.name = 'error_name_2';
+                assert.equal(wasm.error_to_string(error), 'error_name_2');
+            }
+        "#)
+        .test()
+}