<label> should support form association by parser

Source/core/html/HTMLLabelElement.h

Index: Source/core/html/HTMLLabelElement.h
diff --git a/Source/core/html/HTMLLabelElement.h b/Source/core/html/HTMLLabelElement.h
index 7415dcb5a64a1ea08cb6be9e82f641b2c2f2307a..ce49dd2d68c6d870097c5bd527adeb6817b4e036 100644
--- a/Source/core/html/HTMLLabelElement.h
+++ b/Source/core/html/HTMLLabelElement.h
@@ -24,24 +24,33 @@
 #ifndef HTMLLabelElement_h
 #define HTMLLabelElement_h
 
+#include "core/html/FormAssociatedElement.h"
 #include "core/html/HTMLElement.h"
 #include "core/html/LabelableElement.h"
 
 namespace blink {
 
-class HTMLLabelElement FINAL : public HTMLElement {
+class HTMLLabelElement FINAL : public HTMLElement, public FormAssociatedElement {
     DEFINE_WRAPPERTYPEINFO();
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(HTMLLabelElement);
 public:
-    DECLARE_NODE_FACTORY(HTMLLabelElement);
-
+    static PassRefPtrWillBeRawPtr<HTMLLabelElement> create(Document&, HTMLFormElement*);
     LabelableElement* control() const;
 
     virtual bool willRespondToMouseClickEvents() OVERRIDE;
 
+    virtual void trace(Visitor*) OVERRIDE;
+
     virtual HTMLFormElement* formOwner() const OVERRIDE;
 
+
+#if !ENABLE(OILPAN)
+    using Node::ref;
+    using Node::deref;
+#endif
+
 private:
-    explicit HTMLLabelElement(Document&);
+    explicit HTMLLabelElement(Document&, HTMLFormElement*);
     bool isInInteractiveContent(Node*) const;
 
     virtual bool rendererIsFocusable() const OVERRIDE;
@@ -61,9 +70,40 @@ private:
 
     virtual void focus(bool restorePreviousSelection, FocusType) OVERRIDE;
 
+    // FormAssociatedElement methods
+    virtual bool isFormControlElement() const OVERRIDE { return false; }
+    virtual bool isEnumeratable() const OVERRIDE { return false; }
+    virtual bool isLabelElement() const OVERRIDE { return true; }
+#if !ENABLE(OILPAN)
+    virtual void refFormAssociatedElement() OVERRIDE { ref(); }
+    virtual void derefFormAssociatedElement() OVERRIDE { deref(); }
+#endif
+
+    virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
+
     void updateLabel(TreeScope&, const AtomicString& oldForAttributeValue, const AtomicString& newForAttributeValue);
 };
 
+
+template<typename T> inline const T& toElement(const FormAssociatedElement&);
+template<typename T> inline const T* toElement(const FormAssociatedElement*);
+// Make toHTMLLabelElement() accept a FormAssociatedElement as input instead of a Node.
+template<> inline const HTMLLabelElement* toElement<HTMLLabelElement>(const FormAssociatedElement* element)
+{
+    const HTMLLabelElement* labelElement = static_cast<const HTMLLabelElement*>(element);
+    // FormAssociatedElement doesn't have hasTagName, hence check for assert.
+    ASSERT_WITH_SECURITY_IMPLICATION(!labelElement || labelElement->hasTagName(HTMLNames::labelTag));
+    return labelElement;
+}
+
+template<> inline const HTMLLabelElement& toElement<HTMLLabelElement>(const FormAssociatedElement& element)
+{
+    const HTMLLabelElement& labelElement = static_cast<const HTMLLabelElement&>(element);
+    // FormAssociatedElement doesn't have hasTagName, hence check for assert.
+    ASSERT_WITH_SECURITY_IMPLICATION(labelElement.hasTagName(HTMLNames::labelTag));
+    return labelElement;
+}
+
 } // namespace blink
 
 #endif // HTMLLabelElement_h