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

third_party/WebKit/Source/modules/bluetooth/BluetoothRemoteGATTService.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.
 
 // https://webbluetoothchrome.github.io/web-bluetooth/#idl-def-bluetoothgattservice
 
 // Implement BluetoothRemoteGATTService interface: https://crbug.com/483342
 
 [
-    GarbageCollected,
     OriginTrialEnabled=WebBluetooth,
 ] interface BluetoothRemoteGATTService { // : ServiceEventHandlers {
     readonly    attribute UUID            uuid;
     readonly    attribute boolean         isPrimary;
     // TODO(ortuno): Once device is implemented test that it matches
     // the original device.
     // readonly    attribute BluetoothDevice device;
     [RaisesException, CallWith=ScriptState] Promise<BluetoothRemoteGATTCharacteristic>           getCharacteristic(BluetoothCharacteristicUUID characteristic);
     [RaisesException, CallWith=ScriptState] Promise<sequence<BluetoothRemoteGATTCharacteristic>> getCharacteristics(optional BluetoothCharacteristicUUID characteristic);
     // Promise<BluetoothRemoteGATTService>                  getIncludedService(BluetoothServiceUUID service);
     // Promise<sequence<BluetoothRemoteGATTService>>        getIncludedServices(optional BluetoothServiceUUID service);
 };