Revert "Implement proposed shadow tree cascade order."

Source/core/dom/DocumentOrderedList.h

Index: Source/core/dom/DocumentOrderedList.h
diff --git a/Source/core/dom/DocumentOrderedList.h b/Source/core/dom/DocumentOrderedList.h
index 0acb91bd2d2d75c85d0e5e304ce3bb970f8753b5..7cc6d0f14487e8b128504a9fd54672d467ec372e 100644
--- a/Source/core/dom/DocumentOrderedList.h
+++ b/Source/core/dom/DocumentOrderedList.h
@@ -50,14 +50,10 @@ public:
     size_t size() const { return m_nodes.size(); }
 
     using iterator = WillBeHeapListHashSet<RawPtrWillBeMember<Node>, 32>::iterator;
-    using const_reverse_iterator = WillBeHeapListHashSet<RawPtrWillBeMember<Node>, 32>::const_reverse_iterator;
 
     iterator begin() { return m_nodes.begin(); }
     iterator end() { return m_nodes.end(); }
 
-    const_reverse_iterator rbegin() const { return m_nodes.rbegin(); }
-    const_reverse_iterator rend() const { return m_nodes.rend(); }
-
     DECLARE_TRACE();
 
 private: