[oilpan] Completely move HTMLFormControlElement's hierarchy to the managed heap

Source/core/html/HTMLOptGroupElement.cpp

Index: Source/core/html/HTMLOptGroupElement.cpp
diff --git a/Source/core/html/HTMLOptGroupElement.cpp b/Source/core/html/HTMLOptGroupElement.cpp
index f7da9576654735de5225a906a37dec29578b3f2e..c2b8e86a4b006ba60bc9aa24aa38df3fea2c8c59 100644
--- a/Source/core/html/HTMLOptGroupElement.cpp
+++ b/Source/core/html/HTMLOptGroupElement.cpp
@@ -143,21 +143,21 @@ String HTMLOptGroupElement::groupLabelText() const
     return itemText;
 }
     
-HTMLSelectElement* HTMLOptGroupElement::ownerSelectElement() const
+Result<HTMLSelectElement> HTMLOptGroupElement::ownerSelectElement() const
 {
     ContainerNode* select = parentNode();
     while (select && !select->hasTagName(selectTag))
         select = select->parentNode();
     
     if (!select)
-       return 0;
+        return nullptr;
     
     return toHTMLSelectElement(select);
 }
 
 void HTMLOptGroupElement::accessKeyAction(bool)
 {
-    HTMLSelectElement* select = ownerSelectElement();
+    Handle<HTMLSelectElement> select = ownerSelectElement();
     // send to the parent to bring focus to the list box
     if (select && !select->focused())
         select->accessKeyAction(false);