Rename childNodeCount() / childNode() methods for clarity

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 0303cbb5085f5bb579ac1971a9d3e6e71f0b0a88..f35ea854157a36adaf76b5541c47b71f159e67b4 100644
--- a/Source/core/editing/DeleteSelectionCommand.cpp
+++ b/Source/core/editing/DeleteSelectionCommand.cpp
@@ -501,7 +501,7 @@ void DeleteSelectionCommand::handleGeneralDelete()
                 deleteTextFromNode(text, startOffset, text->length() - startOffset);
                 node = NodeTraversal::next(*node);
             } else {
-                node = startNode->childNode(startOffset);
+                node = startNode->traverseToChildAt(startOffset);
             }
         } else if (startNode == m_upstreamEnd.deprecatedNode() && startNode->isTextNode()) {
             Text* text = toText(m_upstreamEnd.deprecatedNode());