Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/html/HTMLFormControlElement.cpp

Index: Source/core/html/HTMLFormControlElement.cpp
diff --git a/Source/core/html/HTMLFormControlElement.cpp b/Source/core/html/HTMLFormControlElement.cpp
index cdb8c28879ab7bee58146cd00ae2c31a6ea90024..a3edb166c04e6f3bc49970b1778e3e42ebc53e8c 100644
--- a/Source/core/html/HTMLFormControlElement.cpp
+++ b/Source/core/html/HTMLFormControlElement.cpp
@@ -247,6 +247,7 @@ Node::InsertionNotificationRequest HTMLFormControlElement::insertedInto(Containe
 
 void HTMLFormControlElement::removedFrom(ContainerNode* insertionPoint)
 {
+    hideVisibleValidationMessage();

[haraken, 2014/05/06 04:20:16]

I'm curious why the previous code was working without this line.

[Mads Ager (chromium), 2014/05/06 08:26:00]

Because the ValidationMessage destructor did this instead. We cannot let the
destructor do this because we cannot when the document is also dead. If the
document is also dead we don't have to do anything.

     m_validationMessage = nullptr;
     m_ancestorDisabledState = AncestorDisabledStateUnknown;
     m_dataListAncestorState = Unknown;