Have bindings layer assume and insist that all interface types are GCed.

third_party/WebKit/Source/core/html/ValidityState.idl

 /*
  * This file is part of the WebKit project.
  *
  * Copyright (C) 2009 Michelangelo De Simone <micdesim@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 // https://html.spec.whatwg.org/#validitystate
 
 [
-    GarbageCollected
 ] interface ValidityState {
     readonly attribute boolean valueMissing;
     readonly attribute boolean typeMismatch;
     readonly attribute boolean patternMismatch;
     readonly attribute boolean tooLong;
     readonly attribute boolean tooShort;
     readonly attribute boolean rangeUnderflow;
     readonly attribute boolean rangeOverflow;
     readonly attribute boolean stepMismatch;
     readonly attribute boolean badInput;
     readonly attribute boolean customError;
     readonly attribute boolean valid;
 };