Rename childNodeCount() / childNode() methods for clarity

Source/core/page/DOMSelection.cpp

Index: Source/core/page/DOMSelection.cpp
diff --git a/Source/core/page/DOMSelection.cpp b/Source/core/page/DOMSelection.cpp
index fb95fefd6336c95c867903e4134b691e43b274f0..13cc50a45e8aa6a15f705572d9be81b7bbbbc97d 100644
--- a/Source/core/page/DOMSelection.cpp
+++ b/Source/core/page/DOMSelection.cpp
@@ -336,7 +336,7 @@ void DOMSelection::extend(Node* node, int offset, ExceptionState& exceptionState
         exceptionState.throwDOMException(IndexSizeError, String::number(offset) + " is not a valid offset.");
         return;
     }
-    if (offset > (node->offsetInCharacters() ? caretMaxOffset(node) : (int)node->childNodeCount())) {
+    if (offset > (node->offsetInCharacters() ? caretMaxOffset(node) : (int)node->countChildren())) {
         exceptionState.throwDOMException(IndexSizeError, String::number(offset) + " is larger than the given node's length.");
         return;
     }
@@ -481,7 +481,7 @@ void DOMSelection::selectAllChildren(Node* n, ExceptionState& exceptionState)
         return;
 
     // This doesn't (and shouldn't) select text node characters.
-    setBaseAndExtent(n, 0, n, n->childNodeCount(), exceptionState);
+    setBaseAndExtent(n, 0, n, n->countChildren(), exceptionState);
 }
 
 String DOMSelection::toString()