Update API to latest spec : Remove VRFrameData#timestamp

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

 // Copyright 2016 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://w3c.github.io/webvr/#interface-vrframedata
 [
     OriginTrialEnabled=WebVR,
     Constructor,
 ] interface VRFrameData {
-    readonly attribute DOMHighResTimeStamp timestamp;
-
     readonly attribute Float32Array leftProjectionMatrix;
     readonly attribute Float32Array leftViewMatrix;
 
     readonly attribute Float32Array rightProjectionMatrix;
     readonly attribute Float32Array rightViewMatrix;
 
     readonly attribute VRPose pose;
 };