The HTML parser should lazy attach.

Source/core/html/parser/HTMLConstructionSite.cpp

Index: Source/core/html/parser/HTMLConstructionSite.cpp
diff --git a/Source/core/html/parser/HTMLConstructionSite.cpp b/Source/core/html/parser/HTMLConstructionSite.cpp
index fc0e957f39f2071c2c293e7163669f342930eed9..f9878b98705455dd41e43bcad3de3dd2885f83d9 100644
--- a/Source/core/html/parser/HTMLConstructionSite.cpp
+++ b/Source/core/html/parser/HTMLConstructionSite.cpp
@@ -105,7 +105,7 @@ static inline void executeInsertTask(HTMLConstructionSiteTask& task)
 {
     ASSERT(task.operation == HTMLConstructionSiteTask::Insert);
 
-    insert(task, DeprecatedAttachNow);

[eseidel, 2013/09/04 18:39:14]

I assume you meant to include this? :)

[ojan, 2013/09/04 18:43:59]

This is *the* change. Stupid rietveld doesn't update the subject of the issue
when you change the change description.

+    insert(task);
 
     task.child->beginParsingChildren();