LibWeb: Support "importmap" scripts

Author: https://github.com/jamierocks
Commit: e487f70bbf
Pull-request: https://github.com/SerenityOS/serenity/pull/23954
Issue: https://github.com/SerenityOS/serenity/issues/23117

Userland/Libraries/LibWeb/HTML/Scripting/ImportMapParseResult.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2024, Jamie Mansfield <jmansfield@cadixdev.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Heap/Cell.h>
+#include <LibJS/Script.h>
+#include <LibURL/URL.h>
+#include <LibWeb/Forward.h>
+#include <LibWeb/HTML/Scripting/ImportMap.h>
+
+namespace Web::HTML {
+
+// https://html.spec.whatwg.org/multipage/webappapis.html#import-map-parse-result
+class ImportMapParseResult
+    : public JS::Cell
+    , public JS::Script::HostDefined {
+    JS_CELL(Script, JS::Cell);
+    JS_DECLARE_ALLOCATOR(ImportMapParseResult);
+
+public:
+    virtual ~ImportMapParseResult() override;
+
+    static JS::NonnullGCPtr<ImportMapParseResult> create(JS::Realm& realm, ByteString const& input, URL::URL base_url);
+
+    [[nodiscard]] Optional<ImportMap> const& import_map() const { return m_import_map; }
+    void set_import_map(ImportMap const& value) { m_import_map = value; }
+
+    [[nodiscard]] JS::Value error_to_rethrow() const { return m_error_to_rethrow; }
+    void set_error_to_rethrow(JS::Value value) { m_error_to_rethrow = value; }
+
+    void register_import_map(Window& global);
+
+protected:
+    ImportMapParseResult();
+
+    virtual void visit_edges(Visitor&) override;
+
+private:
+    virtual void visit_host_defined_self(JS::Cell::Visitor&) override;
+
+    // https://html.spec.whatwg.org/multipage/webappapis.html#impr-import-map
+    Optional<ImportMap> m_import_map;
+
+    // https://html.spec.whatwg.org/multipage/webappapis.html#impr-error-to-rethrow
+    JS::Value m_error_to_rethrow;
+};
+
+}