MediaStream.ended must return true when it is created with ended tracks.
https://bugs.webkit.org/show_bug.cgi?id=111293

Reviewed by Kentaro Hara.

Source/WebCore:

Spec: http://dev.w3.org/2011/webrtc/editor/getusermedia.html#MediaStream-ended
When a MediaStream object is created, its ended attribute must be set to false,
unless it is being created using the MediaStream() constructor whose arguments
are lists of MediaStreamTrack objects that are all ended, in which case the
MediaStream object must be created with its ended attribute set to true.

Test: fast/mediastream/MediaStreamConstructor.html

* platform/mediastream/MediaStreamDescriptor.h:
(WebCore::MediaStreamDescriptor::MediaStreamDescriptor):

LayoutTests:

* fast/mediastream/MediaStreamConstructor-expected.txt:
* fast/mediastream/MediaStreamConstructor.html:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144623 268f45cc-cd09-0410-ab3c-d52691b4dbfc