Remove the lifetime hack in ImageLoader where it keeps its assoc element alive

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

 /*
  * Copyright (C) 2006, 2007, 2010 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.
  */
 
 // https://html.spec.whatwg.org/#the-embed-element
 
 // TODO(yukishiino): HTMLEmbedElement should not have [OverrideBuiltins].
 [
     OverrideBuiltins,
+    ActiveScriptWrappable,
 ] interface HTMLEmbedElement : HTMLElement {
     [CEReactions, Reflect, URL] attribute DOMString src;
     [CEReactions, Reflect] attribute DOMString type;
     [CEReactions, Reflect] attribute DOMString width;
     [CEReactions, Reflect] attribute DOMString height;
     [CheckSecurity=ReturnValue, RaisesException] Document? getSVGDocument();
 
     // obsolete members
     // https://html.spec.whatwg.org/#HTMLEmbedElement-partial
     [CEReactions, Reflect] attribute DOMString align;
     [CEReactions, Reflect] attribute DOMString name;
 
     // FIXME: None of these getters and setters are in the spec.
     [Custom, NotEnumerable] getter Node (DOMString name);
     [Custom] setter Node (DOMString name, Node value);
 };