Merge pull request #681 from sepiropht/master

[670] add extends for some types

crates/js-sys/tests/wasm/JsString.rs

@@ -1,7 +1,21 @@
 use wasm_bindgen::JsValue;
+use wasm_bindgen::prelude::*;
+use wasm_bindgen::JsCast;
 use wasm_bindgen_test::*;
 use js_sys::*;
 
+#[wasm_bindgen(module = "tests/wasm/JsString.js")]
+extern {
+    fn new_string_object() -> JsValue;
+}
+
+#[wasm_bindgen_test]
+fn js_string_inheritance() {
+    let string = new_string_object();
+    assert!(string.is_instance_of::<JsString>());
+    assert!(string.is_instance_of::<Object>());
+}
+
 #[wasm_bindgen_test]
 fn length() {
     fn test(s: &str) {