s updated when media element is loaded");
                      assert_equals(mediaSource.activeSourceBuffers[0], sourceBuffer,
                        "activeSourceBuffers contains sourceBuffer when media element is loaded");
                      test.done();
                  });
              });
          }, "SourceBuffer added to activeSourceBuffers list when its only video track gets loaded (and thus becomes selected).");

          function mediaSourceActiveSourceBufferOrderTest(addAudioFirst, appen