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

Source/core/html/HTMLKeygenElement.cpp

Index: Source/core/html/HTMLKeygenElement.cpp
diff --git a/Source/core/html/HTMLKeygenElement.cpp b/Source/core/html/HTMLKeygenElement.cpp
index a1ba9662292ca6f099b379f91d460ef0e1de7298..548262c722bbb815831ff001a35553ac28bed892 100644
--- a/Source/core/html/HTMLKeygenElement.cpp
+++ b/Source/core/html/HTMLKeygenElement.cpp
@@ -45,9 +45,14 @@ using namespace HTMLNames;
 
 class KeygenSelectElement : public HTMLSelectElement {
 public:
-    static PassRefPtr<KeygenSelectElement> create(Document* document)
+    static Result<KeygenSelectElement> create(Document* document)
     {
-        return adoptRef(new KeygenSelectElement(document));
+        return adoptNode(new KeygenSelectElement(document));
+    }
+
+    void acceptHeapVisitor(Visitor* visitor) const OVERRIDE
+    {
+        HTMLSelectElement::acceptHeapVisitor(visitor);
     }
 
 protected:
@@ -61,7 +66,7 @@ protected:
 private:
     virtual PassRefPtr<Element> cloneElementWithoutAttributesAndChildren()
     {
-        return create(document());
+        return create(document()).passRefPtr();
     }
 };
 
@@ -75,7 +80,7 @@ inline HTMLKeygenElement::HTMLKeygenElement(const QualifiedName& tagName, Docume
     Vector<String> keys;
     getSupportedKeySizes(keys);
 
-    RefPtr<HTMLSelectElement> select = KeygenSelectElement::create(document);
+    Handle<HTMLSelectElement> select = KeygenSelectElement::create(document);
     for (size_t i = 0; i < keys.size(); ++i) {
         RefPtr<HTMLOptionElement> option = HTMLOptionElement::create(document);
         select->appendChild(option, IGNORE_EXCEPTION);
@@ -85,9 +90,9 @@ inline HTMLKeygenElement::HTMLKeygenElement(const QualifiedName& tagName, Docume
     ensureUserAgentShadowRoot()->appendChild(select, IGNORE_EXCEPTION);
 }
 
-PassRefPtr<HTMLKeygenElement> HTMLKeygenElement::create(const QualifiedName& tagName, Document* document, HTMLFormElement* form)
+Result<HTMLKeygenElement> HTMLKeygenElement::create(const QualifiedName& tagName, Document* document, HTMLFormElement* form)
 {
-    return adoptRef(new HTMLKeygenElement(tagName, document, form));
+    return adoptNode(new HTMLKeygenElement(tagName, document, form));
 }
 
 void HTMLKeygenElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
@@ -120,7 +125,7 @@ const AtomicString& HTMLKeygenElement::formControlType() const
 
 void HTMLKeygenElement::reset()
 {
-    static_cast<HTMLFormControlElement*>(shadowSelect())->reset();
+    Handle<HTMLFormControlElement>::cast(shadowSelect())->reset();
 }
 
 bool HTMLKeygenElement::shouldSaveAndRestoreFormControlState() const
@@ -128,10 +133,15 @@ bool HTMLKeygenElement::shouldSaveAndRestoreFormControlState() const
     return false;
 }
 
-HTMLSelectElement* HTMLKeygenElement::shadowSelect() const
+Result<HTMLSelectElement> HTMLKeygenElement::shadowSelect() const
 {
     ShadowRoot* root = userAgentShadowRoot();
-    return root ? toHTMLSelectElement(root->firstChild()) : 0;
+    return root ? toHTMLSelectElement(root->firstChild()) : nullptr;
+}
+
+void HTMLKeygenElement::acceptHeapVisitor(Visitor* visitor) const
+{
+    HTMLFormControlElementWithState::acceptHeapVisitor(visitor);
 }
 
 } // namespace