LibJS: Implement Wrapped Function Exotic Objects

This is a new concept from the ShadowRealm API stage 3 proposal:
https://tc39.es/proposal-shadowrealm/#sec-wrapped-function-exotic-objects

Userland/Libraries/LibJS/Runtime/ShadowRealm.cpp

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/ShadowRealm.h>
+#include <LibJS/Runtime/WrappedFunction.h>
+
+namespace JS {
+
+// 3.1.3 GetWrappedValue ( callerRealm, value ), https://tc39.es/proposal-shadowrealm/#sec-getwrappedvalue
+ThrowCompletionOr<Value> get_wrapped_value(GlobalObject& global_object, Realm& caller_realm, Value value)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Assert: callerRealm is a Realm Record.
+
+    // 2. If Type(value) is Object, then
+    if (value.is_object()) {
+        // a. If IsCallable(value) is false, throw a TypeError exception.
+        if (!value.is_function())
+            return vm.throw_completion<TypeError>(global_object, ErrorType::ShadowRealmWrappedValueNonFunctionObject, value);
+
+        // b. Return ! WrappedFunctionCreate(callerRealm, value).
+        return { WrappedFunction::create(global_object, caller_realm, value.as_function()) };
+    }
+
+    // 3. Return value.
+    return value;
+}
+
+}