Bug 1850293 - Make validity states non-intrinsic. r=smaug

Add a RAII helper to notify of multiple state changes together for
these.

The UpdateState CustomElementInternals calls that are getting removed
are unnecessary (the state should be up-to-date by then, there's nothing
changing there particularly).

Same for the call in nsGenericHTMLFormElement::UnbindFromTree. ClearForm
already does an state update.

Differential Revision: https://phabricator.services.mozilla.com/D187033

dom/html/HTMLTextAreaElement.h

@@ -71,8 +71,6 @@ class HTMLTextAreaElement final : public TextControlElement,
 
   void FieldSetDisabledChanged(bool aNotify) override;
 
-  ElementState IntrinsicState() const override;
-
   void SetLastValueChangeWasInteractive(bool);
 
   // TextControlElement
@@ -393,6 +391,8 @@ class HTMLTextAreaElement final : public TextControlElement,
   void GetSelectionRange(uint32_t* aSelectionStart, uint32_t* aSelectionEnd,
                          ErrorResult& aRv);
 
+  void UpdateValidityElementStates(bool aNotify) final;
+
  private:
   static void MapAttributesIntoRule(MappedDeclarationsBuilder&);
 };