Fix bug where form/fieldset :valid/:invalid won't be recalculated upon control's willValidate change

Source/core/html/FormAssociatedElement.cpp

Index: Source/core/html/FormAssociatedElement.cpp
diff --git a/Source/core/html/FormAssociatedElement.cpp b/Source/core/html/FormAssociatedElement.cpp
index 0b289f99ee96ed5faf87a16c2761f6e7f943aec6..4e0c19a5ee7b6e795e070465856e1ffa1c5bcb8e 100644
--- a/Source/core/html/FormAssociatedElement.cpp
+++ b/Source/core/html/FormAssociatedElement.cpp
@@ -149,6 +149,11 @@ void FormAssociatedElement::setForm(HTMLFormElement* newForm)
     if (m_form.get() == newForm)
         return;
     willChangeForm();
+#if ENABLE(OILPAN)
+    HTMLFormElement* oldForm = m_form;
+#else
+    HTMLFormElement* oldForm = m_form.get();
+#endif
     if (m_form)
         m_form->disassociate(*this);
     if (newForm) {
@@ -165,14 +170,14 @@ void FormAssociatedElement::setForm(HTMLFormElement* newForm)
         m_form = WeakPtr<HTMLFormElement>();
 #endif
     }
-    didChangeForm();
+    didChangeForm(oldForm);
 }
 
 void FormAssociatedElement::willChangeForm()
 {
 }
 
-void FormAssociatedElement::didChangeForm()
+void FormAssociatedElement::didChangeForm(HTMLFormElement* oldForm)
 {
 }