LibJS: Implement Temporal.now.timeZone()

Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h

@@ -300,6 +300,7 @@ namespace JS {
     P(tanh)                                  \
     P(test)                                  \
     P(then)                                  \
+    P(timeZone)                              \
     P(toDateString)                          \
     P(toFixed)                               \
     P(toGMTString)                           \

Userland/Libraries/LibJS/Runtime/Temporal/Now.cpp

@@ -6,6 +6,7 @@
 
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Temporal/Now.h>
+#include <LibJS/Runtime/Temporal/TimeZone.h>
 
 namespace JS::Temporal {
 
@@ -18,6 +19,28 @@ Now::Now(GlobalObject& global_object)
 void Now::initialize(GlobalObject& global_object)
 {
     Object::initialize(global_object);
+
+    auto& vm = this->vm();
+    u8 attr = Attribute::Writable | Attribute::Configurable;
+
+    define_native_function(vm.names.timeZone, time_zone, 0, attr);
+}
+
+// 2.1.1 Temporal.now.timeZone ( ), https://tc39.es/proposal-temporal/#sec-temporal.now.timezone
+JS_DEFINE_NATIVE_FUNCTION(Now::time_zone)
+{
+    // 1. Return ? SystemTimeZone().
+    return system_time_zone(global_object);
+}
+
+// 2.2.1 SystemTimeZone ( ), https://tc39.es/proposal-temporal/#sec-temporal-systemtimezone
+Object* system_time_zone(GlobalObject& global_object)
+{
+    // 1. Let identifier be ! DefaultTimeZone().
+    auto identifier = default_time_zone();
+
+    // 2. Return ? CreateTemporalTimeZone(identifier).
+    return create_temporal_time_zone(global_object, identifier);
 }
 
 }

Userland/Libraries/LibJS/Runtime/Temporal/Now.h

@@ -17,6 +17,11 @@ public:
     explicit Now(GlobalObject&);
     virtual void initialize(GlobalObject&) override;
     virtual ~Now() override = default;
+
+private:
+    JS_DECLARE_NATIVE_FUNCTION(time_zone);
 };
 
+Object* system_time_zone(GlobalObject&);
+
 }