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

third_party/WebKit/Source/modules/screen_orientation/ScreenOrientation.idl

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 enum OrientationLockType {
     "any",
     "natural",
     "landscape",
     "portrait",
     "portrait-primary",
     "portrait-secondary",
     "landscape-primary",
     "landscape-secondary"
 };
 
 enum OrientationType {
     "portrait-primary",
     "portrait-secondary",
     "landscape-primary",
     "landscape-secondary"
 };
 
 [
-    GarbageCollected,
     RuntimeEnabled=ScreenOrientation
 ] interface ScreenOrientation : EventTarget {
     [MeasureAs=ScreenOrientationAngle] readonly attribute unsigned short angle;
     [MeasureAs=ScreenOrientationType] readonly attribute DOMString type;
 
     [CallWith=ScriptState, MeasureAs=ScreenOrientationLock] Promise lock(OrientationLockType orientation);
     [MeasureAs=ScreenOrientationUnlock] void unlock();
 
     attribute EventHandler onchange;
 };