LibWeb: Begin implementing the drag data store

(cherry picked from commit 9e98e63559ebaaf50e7260c62ea750869bb3613d)

Userland/Libraries/LibWeb/HTML/DragDataStore.cpp

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/HTML/DataTransfer.h>
+#include <LibWeb/HTML/DragDataStore.h>
+
+namespace Web::HTML {
+
+DragDataStore::DragDataStore()
+    : m_allowed_effects_state(DataTransferEffect::uninitialized)
+{
+}
+
+DragDataStore::~DragDataStore() = default;
+
+bool DragDataStore::has_text_item() const
+{
+    for (auto const& item : m_item_list) {
+        if (item.kind == DragDataStoreItem::Kind::Text && item.type_string == "text/plain"sv)
+            return true;
+    }
+
+    return false;
+}
+
+}