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

third_party/WebKit/Source/modules/vr/VRDevice.idl

 // Copyright 2015 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.
 
 // http://mozvr.github.io/webvr-spec/webvr.html#vrdevice
 [
     RuntimeEnabled=WebVR,
-    GarbageCollected,
 ] interface VRDevice {
     // An identifier for the distinct hardware unit that this
     // VR Device is a part of.  All VRDevice/Sensors that come
     // from the same hardware will have the same hardwareId.
     readonly attribute DOMString hardwareUnitId;
 
     // An identifier for this distinct sensor/device on a physical
     // hardware device.  This shouldn't change across browser
     // restrats, allowing configuration data to be saved based on it.
     readonly attribute DOMString deviceId;
 
     // A user-readable name identifying the device.
     readonly attribute DOMString deviceName;
 };