LibJS: Add a barebones SourceTextModule class

This corresponds to "Source Text Module Record" from the spec.

Userland/Libraries/LibJS/SourceTextModule.cpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/SourceTextModule.h>
+
+namespace JS {
+
+// 16.2.1.6.1 ParseModule ( sourceText, realm, hostDefined ), https://tc39.es/ecma262/#sec-parsemodule
+Result<NonnullRefPtr<SourceTextModule>, Vector<Parser::Error>> SourceTextModule::parse(StringView source_text, Realm& realm, [[maybe_unused]] StringView filename)
+{
+    // 1. Let body be ParseText(sourceText, Module).
+    auto parser = Parser(Lexer(source_text, filename), Program::Type::Module);
+    auto body = parser.parse_program();
+
+    // 2. If body is a List of errors, return body.
+    if (parser.has_errors())
+        return parser.errors();
+
+    // FIXME: Implement the rest of ParseModule.
+    return adopt_ref(*new SourceTextModule(realm, move(body)));
+}
+
+SourceTextModule::SourceTextModule(Realm& realm, NonnullRefPtr<Program> program)
+    : Module(realm)
+    , m_ecmascript_code(move(program))
+{
+}
+
+SourceTextModule::~SourceTextModule()
+{
+}
+
+}