LibJS: Add the remaining generator objects

- %GeneratorFunction%
- %GeneratorFunction.prototype%
- %GeneratorFunction.prototype.prototype%
- %Generator%.prototype

Userland/Libraries/LibJS/Runtime/GeneratorFunctionConstructor.cpp

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2021, Matthew Olsson <mattco@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/FunctionConstructor.h>
+#include <LibJS/Runtime/Function.h>
+#include <LibJS/Runtime/GeneratorFunctionConstructor.h>
+#include <LibJS/Runtime/GlobalObject.h>
+
+namespace JS {
+
+GeneratorFunctionConstructor::GeneratorFunctionConstructor(GlobalObject& global_object)
+    : NativeFunction(*static_cast<Object*>(global_object.function_constructor()))
+{
+}
+
+void GeneratorFunctionConstructor::initialize(GlobalObject& global_object)
+{
+    auto& vm = this->vm();
+    NativeFunction::initialize(global_object);
+
+    // 27.3.2.1 GeneratorFunction.length, https://tc39.es/ecma262/#sec-generatorfunction.length
+    define_property(vm.names.length, Value(1), Attribute::Configurable);
+    // 27.3.2.2 GeneratorFunction.prototype, https://tc39.es/ecma262/#sec-generatorfunction.length
+    define_property(vm.names.prototype, global_object.generator_function_prototype(), 0);
+}
+
+GeneratorFunctionConstructor::~GeneratorFunctionConstructor()
+{
+}
+
+// 27.3.1.1 GeneratorFunction ( p1, p2, … , pn, body ), https://tc39.es/ecma262/#sec-generatorfunction
+Value GeneratorFunctionConstructor::call()
+{
+    return construct(*this);
+}
+
+// 27.3.1.1 GeneratorFunction ( p1, p2, … , pn, body ), https://tc39.es/ecma262/#sec-generatorfunction
+Value GeneratorFunctionConstructor::construct(Function&)
+{
+    TODO();
+}
+
+}