Create bindings for RegExp (#580)

* Create bindings for RegExp

* Address review comments

- Split the constructor into two: `new` and `new_regexp`. This way we
  can write RegExp::new("foo", "g") rather than
  RegExp::new(&JsValue::from("foo"), "g").

- The js_name for the setter for lastIndex should be `lastIndex` and
  not `set_lastIndex`. But fixing this causes a panic. Remove the
  method for now.

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

@@ -0,0 +1,126 @@
+use wasm_bindgen::JsValue;
+use wasm_bindgen_test::*;
+use js_sys::*;
+
+#[wasm_bindgen_test]
+fn exec() {
+
+    let re = RegExp::new("quick\\s(brown).+?(jumps)", "ig");
+    let result = re.exec("The Quick Brown Fox Jumps Over The Lazy Dog");
+
+    let mut v = vec![];
+    result.unwrap().for_each(&mut |x, _, _| v.push(x));
+
+    assert_eq!(v[0], "Quick Brown Fox Jumps");
+    assert_eq!(v[1], "Brown");
+    assert_eq!(v[2], "Jumps");
+
+    let result = re.exec("foo");
+    assert!(result.is_none());
+}
+
+#[wasm_bindgen_test]
+fn flags() {
+    let re = RegExp::new("foo", "ig");
+    assert_eq!(re.flags(), "gi");
+}
+
+#[wasm_bindgen_test]
+fn global() {
+    let re = RegExp::new("foo", "g");
+    assert!(re.global());
+
+    let re = RegExp::new("bar", "i");
+    assert!(!re.global());
+}
+
+#[wasm_bindgen_test]
+fn ignore_case() {
+    let re = RegExp::new("foo", "");
+    assert!(!re.ignore_case());
+
+    let re = RegExp::new("foo", "i");
+    assert!(re.ignore_case());
+}
+
+#[wasm_bindgen_test]
+fn input() {
+    let re = RegExp::new("hi", "g");
+    re.test("hi there!");
+    assert_eq!(RegExp::input(), "hi there!");
+}
+
+#[wasm_bindgen_test]
+fn last_match() {
+    let re = RegExp::new("hi", "g");
+    re.test("hi there!");
+    assert_eq!(RegExp::last_match(), "hi");
+}
+
+#[wasm_bindgen_test]
+fn last_paren() {
+    let re = RegExp::new("(hi)", "g");
+    re.test("hi there!");
+    assert_eq!(RegExp::last_paren(), "hi");
+}
+
+#[wasm_bindgen_test]
+fn left_context() {
+    let re = RegExp::new("world", "g");
+    re.test("hello world!");
+    assert_eq!(RegExp::left_context(), "hello ");
+}
+
+#[wasm_bindgen_test]
+fn multiline() {
+    let re = RegExp::new("foo", "m");
+    assert!(re.multiline());
+}
+
+#[wasm_bindgen_test]
+fn new() {
+    let re = RegExp::new("foo", "");
+    let re = RegExp::new_regexp(&re, "g");
+    assert_eq!(re.to_string(), "/foo/g");
+}
+
+#[wasm_bindgen_test]
+fn right_context() {
+    let re = RegExp::new("hello", "g");
+    re.test("hello world!");
+    assert_eq!(RegExp::right_context(), " world!");
+}
+
+#[wasm_bindgen_test]
+fn source() {
+    let re = RegExp::new("fooBar", "ig");
+    assert_eq!(re.source(), "fooBar");
+
+    let re = RegExp::new("", "ig");
+    assert_eq!(re.source(), "(?:)");
+}
+
+#[wasm_bindgen_test]
+fn sticky() {
+    let re = RegExp::new("foo", "y");
+    assert!(re.sticky());
+}
+
+#[wasm_bindgen_test]
+fn test() {
+    let re = RegExp::new("foo", "");
+    assert!(re.test("football"));
+    assert!(!re.test("bar"));
+}
+
+#[wasm_bindgen_test]
+fn to_string() {
+    let re = RegExp::new("a+b+c", "g");
+    assert_eq!(re.to_string(), "/a+b+c/g");
+}
+
+#[wasm_bindgen_test]
+fn unicode() {
+    let re = RegExp::new("\u{61}", "u");
+    assert!(re.unicode());
+}

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

@@ -25,6 +25,7 @@ pub mod Number;
 pub mod Object;
 pub mod Proxy;
 pub mod Reflect;
+pub mod RegExp;
 pub mod Set;
 pub mod SetIterator;
 pub mod Symbol;