Add MediaStream.active attribute

LayoutTests/fast/mediastream/RTCPeerConnection-remotestreams.html

Index: LayoutTests/fast/mediastream/RTCPeerConnection-remotestreams.html
diff --git a/LayoutTests/fast/mediastream/RTCPeerConnection-remotestreams.html b/LayoutTests/fast/mediastream/RTCPeerConnection-remotestreams.html
index 8e46faea26198e747e493880c3580c1d37f0aa65..c1616468e5fc9426b773f8b41d98f811b684ad65 100644
--- a/LayoutTests/fast/mediastream/RTCPeerConnection-remotestreams.html
+++ b/LayoutTests/fast/mediastream/RTCPeerConnection-remotestreams.html
@@ -58,6 +58,7 @@ function onAddStream(event) {
     testPassed('remote stream was added');
     shouldBeEqualToNumber('event.stream.getVideoTracks().length', 1);
     shouldBeEqualToNumber('event.stream.getAudioTracks().length', 1);
+    shouldBeTrue('event.stream.active')
     pc.removeStream(local_stream);
 }
 
@@ -65,6 +66,7 @@ function onRemoveStream(event) {
     testPassed('remote stream was removed');
     shouldBeEqualToNumber('event.stream.getVideoTracks().length', 0);
     shouldBeEqualToNumber('event.stream.getAudioTracks().length', 0);
+    shouldBeFalse('event.stream.active')
 }
 
 pc = new webkitRTCPeerConnection(null, null);