MediaRecorder: support |timecode| and remove |m_ignoreMutedMedia|.

third_party/WebKit/Source/modules/mediarecorder/MediaRecorder.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://w3c.github.io/mediacapture-record/MediaRecorder.html#MediaRecorderAPI
 
 enum RecordingState { "inactive", "recording", "paused" };
 
 [
     ActiveScriptWrappable,
     ConstructorCallWith=ExecutionContext,
     Constructor(MediaStream stream, optional MediaRecorderOptions options),
     DependentLifetime,
     RaisesException=Constructor,
 ] interface MediaRecorder : EventTarget {
     readonly attribute MediaStream stream;
     readonly attribute DOMString mimeType;
     readonly attribute RecordingState state;
 
     attribute EventHandler onstart;
     attribute EventHandler onstop;
     attribute EventHandler ondataavailable;
     attribute EventHandler onpause;
     attribute EventHandler onresume;
     attribute EventHandler onerror;
-    attribute boolean ignoreMutedMedia;
     readonly attribute unsigned long videoBitsPerSecond;
     readonly attribute unsigned long audioBitsPerSecond;
 
     [RaisesException, Measure] void start(optional long timeslice);
     [RaisesException] void stop();
     [RaisesException] void pause();
     [RaisesException] void resume();
     [RaisesException] void requestData();
 
     static boolean isTypeSupported(DOMString type);
 };