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/Runtime/Temporal/Now.h

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
+ * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibCrypto/BigInt/SignedBigInteger.h>
+#include <LibJS/Runtime/Completion.h>
+#include <LibJS/Runtime/Object.h>
+
+namespace JS::Temporal {
+
+class Now final : public Object {
+    JS_OBJECT(Now, Object);
+    GC_DECLARE_ALLOCATOR(Now);
+
+public:
+    virtual void initialize(Realm&) override;
+    virtual ~Now() override = default;
+
+private:
+    explicit Now(Realm&);
+
+    JS_DECLARE_NATIVE_FUNCTION(time_zone_id);
+    JS_DECLARE_NATIVE_FUNCTION(instant);
+    JS_DECLARE_NATIVE_FUNCTION(plain_date_time_iso);
+    JS_DECLARE_NATIVE_FUNCTION(plain_date_iso);
+    JS_DECLARE_NATIVE_FUNCTION(plain_time_iso);
+};
+
+Crypto::SignedBigInteger system_utc_epoch_nanoseconds(VM&);
+ThrowCompletionOr<ISODateTime> system_date_time(VM&, Value temporal_time_zone_like);
+
+}