Avoid N^2 walk placing renderers when building the render tree

Source/core/html/HTMLInputElement.cpp

Index: Source/core/html/HTMLInputElement.cpp
diff --git a/Source/core/html/HTMLInputElement.cpp b/Source/core/html/HTMLInputElement.cpp
index e832e65abc5e3970dbf792e23f5e1146a3351523..9c38f7cee41bfb0cbeb0cce31ed78b41813d4bdd 100644
--- a/Source/core/html/HTMLInputElement.cpp
+++ b/Source/core/html/HTMLInputElement.cpp
@@ -1475,11 +1475,18 @@ void HTMLInputElement::didChangeForm()
     addToRadioButtonGroup();
 }
 
+void HTMLInputElement::addToRadioButtonGroupCallback(Node* node)
+{
+    ASSERT(node && node->toInputElement());
+    HTMLInputElement* inputElement = node->toInputElement();
+    inputElement->addToRadioButtonGroup();
+}
+
 Node::InsertionNotificationRequest HTMLInputElement::insertedInto(ContainerNode* insertionPoint)
 {
     HTMLTextFormControlElement::insertedInto(insertionPoint);
-    if (insertionPoint->inDocument() && !form())
-        addToRadioButtonGroup();
+    if (insertionPoint->inDocument() && !form() && checkedRadioButtons())
+        queueInsertionCallback(addToRadioButtonGroupCallback, this);
     resetListAttributeTargetObserver();
     return InsertionDone;
 }