LibWeb: Preserve indeterminate value when cloning HTMLInputElement

Author: https://github.com/tcl3
Commit: c87bc78d5d
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3154

Libraries/LibWeb/HTML/HTMLInputElement.cpp

@@ -1721,6 +1721,10 @@ WebIDL::ExceptionOr<void> HTMLInputElement::cloned(DOM::Node& copy, bool subtree
     input_clone.m_dirty_value = m_dirty_value;
     input_clone.m_checked = m_checked;
     input_clone.m_dirty_checkedness = m_dirty_checkedness;
+
+    // AD-HOC: The spec doesn't mention propagating this state, but there is a WPT test that expects cloned nodes to preserve it.
+    input_clone.m_indeterminate = m_indeterminate;
+
     return {};
 }