LibWeb: Provide default text for Reset and Submit buttons

Author: https://github.com/stelar7
Commit: 056b774b1e
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3165
Reviewed-by: https://github.com/tcl3 ✅

Libraries/LibWeb/HTML/HTMLInputElement.h

@@ -306,6 +306,8 @@ private:
     GC::Ptr<DOM::Element> m_placeholder_element;
     GC::Ptr<DOM::Text> m_placeholder_text_node;
 
+    void update_button_input_shadow_tree();
+
     void update_text_input_shadow_tree();
     GC::Ptr<DOM::Element> m_inner_text_element;
     GC::Ptr<DOM::Text> m_text_node;