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

Source/core/html/HTMLFormElement.h

Index: Source/core/html/HTMLFormElement.h
diff --git a/Source/core/html/HTMLFormElement.h b/Source/core/html/HTMLFormElement.h
index cf6f6896714cf29ad6fd30e121c19e7fb8042131..b8e49f6fcd683d9cb41c4c716685e613133f670a 100644
--- a/Source/core/html/HTMLFormElement.h
+++ b/Source/core/html/HTMLFormElement.h
@@ -48,7 +48,7 @@ public:
     virtual ~HTMLFormElement();
     virtual void trace(Visitor*) override;
 
-    void setNeedsValidityCheck();
+    void setNeedsValidityCheck(ValidityRecalcReason, bool isValid);
 
     PassRefPtrWillBeRawPtr<HTMLFormControlsCollection> elements();
     void getNamedElements(const AtomicString&, WillBeHeapVector<RefPtrWillBeMember<Element> >&);
@@ -186,6 +186,10 @@ private:
 
     bool m_wasDemoted : 1;
 
+    // Number of invalid elements associated to the form that are candidates
+    // for constraint validation (their willValidate state is true).
+    int m_invalidControlsCount;
+
     OwnPtrWillBeMember<GenericEventQueue> m_pendingAutocompleteEventsQueue;
 };