LibWeb: Stub out a basic Selection interface

This patch establishes scaffolding for the Selection API.

Userland/Libraries/LibWeb/Selection/Selection.cpp

@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/Selection/Selection.h>
+
+namespace Web::Selection {
+
+NonnullRefPtr<Selection> Selection::create()
+{
+    return adopt_ref(*new Selection);
+}
+
+DOM::Node* Selection::anchor_node()
+{
+    TODO();
+}
+
+unsigned Selection::anchor_offset()
+{
+    TODO();
+}
+
+DOM::Node* Selection::focus_node()
+{
+    TODO();
+}
+
+unsigned Selection::focus_offset() const
+{
+    TODO();
+}
+
+bool Selection::is_collapsed() const
+{
+    TODO();
+}
+
+unsigned Selection::range_count() const
+{
+    TODO();
+}
+
+String Selection::type() const
+{
+    TODO();
+}
+
+NonnullRefPtr<DOM::Range> Selection::get_range_at(unsigned index)
+{
+    (void)index;
+    TODO();
+}
+
+void Selection::add_range(DOM::Range&)
+{
+    TODO();
+}
+
+void Selection::remove_range(DOM::Range&)
+{
+    TODO();
+}
+
+void Selection::remove_all_ranges()
+{
+    TODO();
+}
+
+void Selection::empty()
+{
+    TODO();
+}
+
+void Selection::collapse(DOM::Node*, unsigned offset)
+{
+    (void)offset;
+    TODO();
+}
+
+void Selection::set_position(DOM::Node*, unsigned offset)
+{
+    (void)offset;
+    TODO();
+}
+
+void Selection::collapse_to_start()
+{
+    TODO();
+}
+
+void Selection::collapse_to_end()
+{
+    TODO();
+}
+
+void Selection::extend(DOM::Node&, unsigned offset)
+{
+    (void)offset;
+    TODO();
+}
+
+void Selection::set_base_and_extent(DOM::Node& anchor_node, unsigned anchor_offset, DOM::Node& focus_node, unsigned focus_offset)
+{
+    (void)anchor_node;
+    (void)anchor_offset;
+    (void)focus_node;
+    (void)focus_offset;
+    TODO();
+}
+
+void Selection::select_all_children(DOM::Node&)
+{
+    TODO();
+}
+
+void Selection::delete_from_document()
+{
+    TODO();
+}
+
+bool Selection::contains_node(DOM::Node&, bool allow_partial_containment) const
+{
+    (void)allow_partial_containment;
+    TODO();
+}
+
+String Selection::to_string() const
+{
+    TODO();
+}
+
+}