LibWeb: Port node text content to UTF-16

Author: https://github.com/trflynn89
Commit: 5c561c1a53
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5627
Reviewed-by: https://github.com/gmta ✅

Libraries/LibWeb/HTML/HTMLDetailsElement.cpp

@@ -252,7 +252,7 @@ WebIDL::ExceptionOr<void> HTMLDetailsElement::create_shadow_tree_if_needed()
         :host([open]) summary {
             list-style-type: disclosure-open;
         }
-    )~~~"_string);
+    )~~~"_utf16);
     MUST(shadow_root->append_child(style));
 
     m_summary_slot = static_cast<HTML::HTMLSlotElement&>(*summary_slot);