LibWeb: Add implementation of Node.compareDocumentPosition()

While looking into getting Duck Duck Go loading further in the
Browser, I noticed that it was complaining about the missing
method Node.compareDocumentPosition.

This change implements as much of the DOM spec as possible
with the current implementation of the DOM to date. The
implementation is validated by new tests in the Node.js.

1 files changed, 1 insertions, 0 deletions

diff --git a/Userland/Libraries/LibWeb/DOM/Node.h b/Userland/Libraries/LibWeb/DOM/Node.h
index 946279ae45..0cb36d0113 100644
--- a/Userland/Libraries/LibWeb/DOM/Node.h
+++ b/Userland/Libraries/LibWeb/DOM/Node.h
@@ -100,6 +100,7 @@ public:
     void insert_before(NonnullRefPtr<Node> node, RefPtr<Node> child, bool suppress_observers = false);
     void remove(bool suppress_observers = false);
     void remove_all_children(bool suppress_observers = false);
+    u16 compare_document_position(RefPtr<Node> other);
 
     // NOTE: This is intended for the JS bindings.
     bool has_child_nodes() const { return has_children(); }