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

third_party/WebKit/Source/core/css/CSSStyleDeclaration.idl

 /*
  * Copyright (C) 2006, 2007, 2009 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.
  */
 
 // http://dev.w3.org/csswg/cssom/#the-cssstyledeclaration-interface
 
 [
     DependentLifetime,
-    GarbageCollected
 ] interface CSSStyleDeclaration {
     [RaisesException=Setter] attribute DOMString cssText;
     readonly attribute unsigned long length;
     getter DOMString item(unsigned long index);
     DOMString getPropertyValue(DOMString property);
     DOMString getPropertyPriority(DOMString property);
     // TODO(philipj): The value and priority arguments should have
     // [TreatNullAs=EmptyString] and should not be nullable.
     [RaisesException] void setProperty(DOMString property, DOMString? value, optional DOMString? priority = null);
     // void setPropertyValue(DOMString property, [TreatNullAs=EmptyString] DOMString value);
     // void setPropertyPriority(DOMString property, [TreatNullAs=EmptyString] DOMString priority);
     [RaisesException] DOMString removeProperty(DOMString property);
     readonly attribute CSSRule? parentRule;
     [RaisesException=Setter, TreatNullAs=EmptyString] attribute DOMString cssFloat;
 
     // The camel-cased and dashed attribute getters have custom bindings.
     // http://dev.w3.org/csswg/cssom/#dom-cssstyledeclaration-camel-cased-attribute
     // http://dev.w3.org/csswg/cssom/#dom-cssstyledeclaration-dashed-attribute
     [Custom=(PropertyGetter,PropertyEnumerator,PropertyQuery)] getter (DOMString or float) (DOMString name);
     [Custom] setter void (DOMString property, DOMString? propertyValue);
 };