Use ContainerNode::hasChildren() instead of firstChild() in conditionals

Source/core/dom/NodeTraversal.h

Index: Source/core/dom/NodeTraversal.h
diff --git a/Source/core/dom/NodeTraversal.h b/Source/core/dom/NodeTraversal.h
index a3dbe6ed57f75c3530b24ad318694325a7c1d3c9..c82aff81483c0c4d40c30bbaccc8bf0f53d86afa 100644
--- a/Source/core/dom/NodeTraversal.h
+++ b/Source/core/dom/NodeTraversal.h
@@ -76,7 +76,7 @@ private:
 template <class NodeType>
 inline Node* NodeTraversal::traverseNextTemplate(NodeType& current)
 {
-    if (current.firstChild())
+    if (current.hasChildren())
         return current.firstChild();
     if (current.nextSibling())
         return current.nextSibling();
@@ -86,7 +86,7 @@ inline Node* NodeTraversal::traverseNextTemplate(NodeType& current)
 template <class NodeType>
 inline Node* NodeTraversal::traverseNextTemplate(NodeType& current, const Node* stayWithin)
 {
-    if (current.firstChild())
+    if (current.hasChildren())
         return current.firstChild();
     if (current == stayWithin)
         return 0;