bindings: Supports inheritance of [Unforgeable] attributes as accessor-type properties.

Source/core/html/HTMLDocument.idl

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@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.
  */
 
 // FIXME: "For historical reasons, Window objects must also have a
 // writable, configurable, non-enumerable property named HTMLDocument
 // whose value is the Document interface object."
 // https://html.spec.whatwg.org/#the-window-object
 
 interface HTMLDocument : Document {
-    // Inheritance of [Unforgeable] attributes is not supported.  So we have to
-    // define the same unforgeable attributes in derived interfaces as well.
-    // See that Document already defined 'location' attribute and this interface
-    // redefine it.
-    // Keep all the definitions consistent.
-    // TODO(yukishiino): Support inheritance of attributes defined on instance.
-    [PutForwards=href, Unforgeable] readonly attribute Location? location;
-
     // https://html.spec.whatwg.org/#Document-partial
 
     // FIXME: *Color should have [TreatNullAs=EmptyString].
     [TreatNullAs=NullString, CustomElementCallbacks] attribute DOMString fgColor;
     [TreatNullAs=NullString, CustomElementCallbacks] attribute DOMString linkColor;
     [TreatNullAs=NullString, CustomElementCallbacks] attribute DOMString vlinkColor;
     [TreatNullAs=NullString, CustomElementCallbacks] attribute DOMString alinkColor;
     [TreatNullAs=NullString, CustomElementCallbacks] attribute DOMString bgColor;
 
     [MeasureAs=DocumentClear] void clear();
     [MeasureAs=DocumentCaptureEvents] void captureEvents();
     [MeasureAs=DocumentReleaseEvents] void releaseEvents();
 
     // FIXME: all should not be [Replaceable].
     [Replaceable, ImplementedAs=allForBinding] readonly attribute HTMLAllCollection all;
 };