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

Source/core/html/HTMLSelectElement.cpp

Index: Source/core/html/HTMLSelectElement.cpp
diff --git a/Source/core/html/HTMLSelectElement.cpp b/Source/core/html/HTMLSelectElement.cpp
index 96e5e479111152e504d2134c44ee49d59798e265..d070c16bd0adbaab735fbbb0c747839034b4052c 100644
--- a/Source/core/html/HTMLSelectElement.cpp
+++ b/Source/core/html/HTMLSelectElement.cpp
@@ -84,10 +84,10 @@ HTMLSelectElement::HTMLSelectElement(const QualifiedName& tagName, Document* doc
     ScriptWrappable::init(this);
 }
 
-PassRefPtr<HTMLSelectElement> HTMLSelectElement::create(const QualifiedName& tagName, Document* document, HTMLFormElement* form)
+Result<HTMLSelectElement> HTMLSelectElement::create(const QualifiedName& tagName, Document* document, HTMLFormElement* form)
 {
     ASSERT(tagName.matches(selectTag));
-    return adoptRef(new HTMLSelectElement(tagName, document, form));
+    return adoptNode(new HTMLSelectElement(tagName, document, form));
 }
 
 const AtomicString& HTMLSelectElement::formControlType() const
@@ -1566,4 +1566,9 @@ unsigned HTMLSelectElement::length() const
     return options;
 }
 
+void HTMLSelectElement::acceptHeapVisitor(Visitor* visitor) const
+{
+    HTMLFormControlElementWithState::acceptHeapVisitor(visitor);
+}
+
 } // namespace