Use sequence<T> instead of T[] where possible and document exceptions

third_party/WebKit/Source/modules/mediasource/TrackDefault.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.
 
 // Per 11 Nov 2014 Editor's Draft
 // https://dvcs.w3.org/hg/html-media/raw-file/tip/media-source/media-source.html#idl-def-TrackDefault
 
 enum TrackDefaultType { "audio", "video", "text" };
 
 [
     Constructor(TrackDefaultType type, DOMString language, DOMString label, sequence<DOMString> kinds, optional DOMString byteStreamTrackID = ""),
     RaisesException=Constructor,
     RuntimeEnabled=MediaSourceExperimental,
 ] interface TrackDefault {
     readonly attribute TrackDefaultType type;
     readonly attribute DOMString byteStreamTrackID;
     readonly attribute DOMString language;
     readonly attribute DOMString label;
+    // TODO(wolenetz): |kinds| should be FrozenArray<DOMString>.

[wolenetz, 2016/10/03 20:53:03]

LGTM % reference https://crbug.com/619665 here please. Note, v1 MSE spec dropped
this feature, but it'll likely come back in incubation. Right before it was
dropped, this attribute was changed to sequence<DOMString> getKinds() accessor.
That crbug tracks updating this object to that latter change.

[foolip, 2016/10/04 10:02:20]

Referencing https://crbug.com/619665 and
https://github.com/w3c/media-source/issues/91.

FWIW, if the constructor is the only way to create an object like this, I think
that a [SameObject] FrozenArray<DOMString> would have been more in line with
other APIs like https://notifications.spec.whatwg.org/#api

     readonly attribute DOMString[] kinds;
 };