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

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index bc827e935ed966e8c3ff5d55d85d4bbf183eedde..a5bcd2e1bcfd4c3882b61ca5016fb83d540b70d5 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -1673,7 +1673,7 @@ void Document::recalcStyle(StyleChange change)
                 renderer()->setStyle(documentStyle.release());
         }
 
-        for (Node* n = lastChild(); n; n = n->previousSibling()) {
+        for (Node* n = firstChild(); n; n = n->nextSibling()) {
             if (!n->isElementNode())
                 continue;
             Element* element = toElement(n);