LibWeb/DOM: Move "text node directionality" algorithm into DOM::Text

Author: https://github.com/AtkinsSJ
Commit: 2a5390ef4f
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1426

Userland/Libraries/LibWeb/DOM/Text.h

@@ -8,6 +8,7 @@
 #pragma once
 
 #include <LibWeb/DOM/CharacterData.h>
+#include <LibWeb/DOM/Element.h>
 #include <LibWeb/DOM/Slottable.h>
 
 namespace Web::DOM {
@@ -48,6 +49,8 @@ public:
     bool is_password_input() const { return m_is_password_input; }
     void set_is_password_input(Badge<HTML::HTMLInputElement>, bool b) { m_is_password_input = b; }
 
+    Optional<Element::Directionality> directionality() const;
+
 protected:
     Text(Document&, String const&);
     Text(Document&, NodeType, String const&);