Rename Node::lastDescendant() / Node::highestAncestor() for clarity

Source/core/editing/ReplaceSelectionCommand.cpp

Index: Source/core/editing/ReplaceSelectionCommand.cpp
diff --git a/Source/core/editing/ReplaceSelectionCommand.cpp b/Source/core/editing/ReplaceSelectionCommand.cpp
index c6eacb9179ae4af0fd92ded0e9c04e3d282d46b6..aa972f87cc340f559a61d2e826795af0da3b96ee 100644
--- a/Source/core/editing/ReplaceSelectionCommand.cpp
+++ b/Source/core/editing/ReplaceSelectionCommand.cpp
@@ -1462,7 +1462,7 @@ void ReplaceSelectionCommand::updateNodesInserted(Node *node)
     if (m_startOfInsertedContent.isNull())
         m_startOfInsertedContent = firstPositionInOrBeforeNode(node);
 
-    m_endOfInsertedContent = lastPositionInOrAfterNode(&node->lastDescendant());
+    m_endOfInsertedContent = lastPositionInOrAfterNode(&node->lastDescendantOrSelf());
 }
 
 // During simple pastes, where we're just pasting a text node into a run of text, we insert the text node