Revert 151996 "Avoid N^2 walk placing renderers when building th..."

Source/core/dom/ContainerNode.h

Index: Source/core/dom/ContainerNode.h
diff --git a/Source/core/dom/ContainerNode.h b/Source/core/dom/ContainerNode.h
index 5578966df32eedad468284a8829ff6392f06ff7a..adc8832d444163d56d6a690659f10e5a484e6eff 100644
--- a/Source/core/dom/ContainerNode.h
+++ b/Source/core/dom/ContainerNode.h
@@ -37,7 +37,7 @@ class HTMLCollection;
 
 typedef void (*NodeCallback)(Node*);
 
-namespace Private { 
+namespace Private {
     template<class GenericNode, class GenericNodeContainer>
     void addChildNodesToDeletionQueue(GenericNode*& head, GenericNode*& tail, GenericNodeContainer*);
 };
@@ -80,7 +80,6 @@ private:
 
 class ContainerNode : public Node {
     friend class PostAttachCallbackDisabler;
-    friend class InsertionCallbackDeferer;
 public:
     virtual ~ContainerNode();
 
@@ -142,8 +141,6 @@ public:
 protected:
     ContainerNode(TreeScope*, ConstructionType = CreateContainer);
 
-    static void queueInsertionCallback(NodeCallback, Node*);
-    static bool insertionCallbacksAreSuspended();
     static void queuePostAttachCallback(NodeCallback, Node*);
     static bool postAttachCallbacksAreSuspended();
 
@@ -166,11 +163,6 @@ private:
     void suspendPostAttachCallbacks();
     void resumePostAttachCallbacks();
 
-    static void dispatchInsertionCallbacks();
-
-    static void suspendInsertionCallbacks();
-    static void resumeInsertionCallbacks();
-
     bool getUpperLeftCorner(FloatPoint&) const;
     bool getLowerRightCorner(FloatPoint&) const;
 
@@ -297,7 +289,7 @@ class ChildNodesLazySnapshot {
     WTF_MAKE_FAST_ALLOCATED;
 public:
     explicit ChildNodesLazySnapshot(Node* parentNode)
-        : m_currentNode(parentNode->lastChild())
+        : m_currentNode(parentNode->firstChild())
         , m_currentIndex(0)
     {
         m_nextSnapshot = latestSnapshot;
@@ -309,13 +301,13 @@ public:
         latestSnapshot = m_nextSnapshot;
     }
 
-    // Returns 0 if there is no previous Node.
-    PassRefPtr<Node> previousNode()
+    // Returns 0 if there is no next Node.
+    PassRefPtr<Node> nextNode()
     {
         if (LIKELY(!hasSnapshot())) {
             RefPtr<Node> node = m_currentNode;
             if (node)
-                m_currentNode = node->previousSibling();
+                m_currentNode = node->nextSibling();
             return node.release();
         }
         Vector<RefPtr<Node> >& nodeVector = *m_childNodes;
@@ -332,7 +324,7 @@ public:
         Node* node = m_currentNode.get();
         while (node) {
             m_childNodes->append(node);
-            node = node->previousSibling();
+            node = node->nextSibling();
         }
     }
 
@@ -357,22 +349,6 @@ private:
     ChildNodesLazySnapshot* m_nextSnapshot;
 };
 
-// Used to ensure Radio Buttons resolve their checked state in document
-// order when a subtree of them is inserted. This is necessary because
-// we resolve style in reverse document order.
-class InsertionCallbackDeferer {
-public:
-    InsertionCallbackDeferer()
-    {
-        ContainerNode::suspendInsertionCallbacks();
-    }
-
-    ~InsertionCallbackDeferer()
-    {
-        ContainerNode::resumeInsertionCallbacks();
-    }
-};
-
 class PostAttachCallbackDisabler {
 public:
     PostAttachCallbackDisabler(ContainerNode* node)