Update tests for chrome, as MediaStream label, ended attributes and stop() method will be removed

chrome/test/data/extensions/api_test/tab_capture/constraints.js

 // 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.
 
 chrome.test.runTests([
   function supportsMediaConstraints() {
     chrome.tabCapture.capture({
       video: true,
       audio: true,
       videoConstraints: {
           mandatory: {
             maxWidth: 1000,
             minWidth: 300
           }
       }
     }, function(stream) {
       chrome.test.assertTrue(!!stream);
-      stream.stop();
+      stream.getVideoTracks()[0].stop();
+      stream.getAudioTracks()[0].stop();
       chrome.test.succeed();
     });
   },
 
   function rejectsOptionalMediaConstraints() {
     chrome.tabCapture.capture({
       video: true,
       audio: true,
       videoConstraints: {
         mandatory: {
@@ skipping 28 matching lines @@
             notValid: '123'
           }
         }
       }, function(stream) {
         chrome.test.assertTrue(!stream);
         chrome.test.succeed();
       });
     });
   }
 ]);