LibJS: Implement Temporal.Now

Author: https://github.com/trflynn89
Commit: f2c19f96f8
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2557
Reviewed-by: https://github.com/shannonbooth ✅

Libraries/LibJS/Tests/builtins/Temporal/Now/Now.plainTimeISO.js

@@ -0,0 +1,19 @@
+describe("correct behavior", () => {
+    test("length is 0", () => {
+        expect(Temporal.Now.plainTimeISO).toHaveLength(0);
+    });
+
+    test("basic functionality", () => {
+        const plainTime = Temporal.Now.plainTimeISO();
+        expect(plainTime).toBeInstanceOf(Temporal.PlainTime);
+        expect(plainTime.calendarId).toBeUndefined();
+    });
+});
+
+describe("errors", () => {
+    test("invalid time zone name", () => {
+        expect(() => {
+            Temporal.Now.plainTimeISO("foo");
+        }).toThrowWithMessage(RangeError, "Invalid time zone name 'foo");
+    });
+});