The HTML parser should lazy attach.

Source/core/html/parser/HTMLConstructionSite.cpp

 /*
  * Copyright (C) 2010 Google, Inc. All Rights Reserved.
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 88 matching lines @@
     if (task.nextChild)
         task.parent->parserInsertBefore(task.child.get(), task.nextChild.get(), attachBehavior);
     else
         task.parent->parserAppendChild(task.child.get(), attachBehavior);
 }
 
 static inline void executeInsertTask(HTMLConstructionSiteTask& task)
 {
     ASSERT(task.operation == HTMLConstructionSiteTask::Insert);
 
-    insert(task, DeprecatedAttachNow);
+    insert(task);
 
     task.child->beginParsingChildren();
 
     if (task.selfClosing)
         task.child->finishParsingChildren();
 }
 
 static inline void executeReparentTask(HTMLConstructionSiteTask& task)
 {
     ASSERT(task.operation == HTMLConstructionSiteTask::Reparent);
@@ skipping 625 matching lines @@
 {
     HTMLConstructionSiteTask task(HTMLConstructionSiteTask::Insert);
     findFosterSite(task);
     task.child = node;
     ASSERT(task.parent);
 
     m_taskQueue.append(task);
 }
 
 }