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

Source/core/html/HTMLSelectElement.h

Index: Source/core/html/HTMLSelectElement.h
diff --git a/Source/core/html/HTMLSelectElement.h b/Source/core/html/HTMLSelectElement.h
index 39a5cc3c80382cda3be13781fe874dd1786f05f0..150dfa1c6439bfb5e1eb0c9c1efc501948290b23 100644
--- a/Source/core/html/HTMLSelectElement.h
+++ b/Source/core/html/HTMLSelectElement.h
@@ -38,7 +38,7 @@ class HTMLOptionElement;
 
 class HTMLSelectElement : public HTMLFormControlElementWithState, public TypeAheadDataSource {
 public:
-    static PassRefPtr<HTMLSelectElement> create(const QualifiedName&, Document*, HTMLFormElement*);
+    static Result<HTMLSelectElement> create(const QualifiedName&, Document*, HTMLFormElement*);
 
     int selectedIndex() const;
     void setSelectedIndex(int);
@@ -105,6 +105,8 @@ public:
     // For use in the implementation of HTMLOptionElement.
     void optionSelectionStateChanged(HTMLOptionElement*, bool optionIsSelected);
 
+    virtual void acceptHeapVisitor(Visitor*) const OVERRIDE;
+
 protected:
     HTMLSelectElement(const QualifiedName&, Document*, HTMLFormElement*);
 
@@ -207,16 +209,16 @@ inline bool isHTMLSelectElement(const Node* node)
     return node->hasTagName(HTMLNames::selectTag);
 }
 
-inline HTMLSelectElement* toHTMLSelectElement(Node* node)
+inline Result<HTMLSelectElement> toHTMLSelectElement(Node* node)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!node || isHTMLSelectElement(node));
-    return static_cast<HTMLSelectElement*>(node);
+    return Handle<HTMLSelectElement>(static_cast<HTMLSelectElement*>(node));
 }
 
-inline const HTMLSelectElement* toHTMLSelectElement(const Node* node)
+inline Result<const HTMLSelectElement> toHTMLSelectElement(const Node* node)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!node || isHTMLSelectElement(node));
-    return static_cast<const HTMLSelectElement*>(node);
+    return Handle<const HTMLSelectElement>(static_cast<const HTMLSelectElement*>(node));
 }
 
 void toHTMLSelectElement(const HTMLSelectElement*); // This overload will catch anyone doing an unnecessary cast.