Move Node::lastDescendantOrSelf() to NodeTraversal and rename to lastWithinOrSelf()

Source/core/editing/DeleteSelectionCommand.cpp

Index: Source/core/editing/DeleteSelectionCommand.cpp
diff --git a/Source/core/editing/DeleteSelectionCommand.cpp b/Source/core/editing/DeleteSelectionCommand.cpp
index 66ab6ae4aa60e3f5a1f2e4396dac22bd6b386d81..76fdbf5cae0e883828ea0da12e27e29726a57c86 100644
--- a/Source/core/editing/DeleteSelectionCommand.cpp
+++ b/Source/core/editing/DeleteSelectionCommand.cpp
@@ -522,7 +522,7 @@ void DeleteSelectionCommand::handleGeneralDelete()
                 removeNode(node.get());
                 node = nextNode.get();
             } else {
-                Node& n = node->lastDescendantOrSelf();
+                Node& n = NodeTraversal::lastWithinOrSelf(*node);
                 if (m_downstreamEnd.deprecatedNode() == n && m_downstreamEnd.deprecatedEditingOffset() >= caretMaxOffset(&n)) {
                     removeNode(node.get());
                     node = nullptr;