Fix <dialog> centering

Source/WebCore/dom/NodeRenderingContext.cpp

Index: Source/WebCore/dom/NodeRenderingContext.cpp
diff --git a/Source/WebCore/dom/NodeRenderingContext.cpp b/Source/WebCore/dom/NodeRenderingContext.cpp
index 9a19e68d1a5dd7e7a991d069b745a33df01d5139..1093d5d3ec29cb8465b932a6a2e9bc7daedad778 100644
--- a/Source/WebCore/dom/NodeRenderingContext.cpp
+++ b/Source/WebCore/dom/NodeRenderingContext.cpp
@@ -80,7 +80,7 @@ static bool isRendererReparented(const RenderObject* renderer)
     if (renderer->style() && !renderer->style()->flowThread().isEmpty())
         return true;
 #if ENABLE(DIALOG_ELEMENT)
-    if (toElement(renderer->node())->isInTopLayer())
+    if (renderer->isDialog())
         return true;
 #endif
     return false;
@@ -154,7 +154,7 @@ RenderObject* NodeRenderingContext::parentRenderer() const
         return renderer->parent();
 
 #if ENABLE(DIALOG_ELEMENT)
-    if (m_node->isElementNode() && toElement(m_node)->isInTopLayer()) {
+    if (m_node->hasTagName(dialogTag)) {
         // The parent renderer of top layer elements is the RenderView, but only
         // if the normal parent would have had a renderer.
         // FIXME: This behavior isn't quite right as the spec for top layer