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 7404e5a885191d20bf38a323627d2d288cd31fd0..e472fea50c44fea43b8f4988725fe7b428a1370a 100644
--- a/Source/core/html/HTMLFormElement.h
+++ b/Source/core/html/HTMLFormElement.h
@@ -47,7 +47,7 @@ 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> >&);
@@ -185,6 +185,10 @@ 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;
 };