Don't include abort() cost when timing MSE methods.

tools/perf/page_sets/mse_cases/startup_test.js

 // Copyright 2013 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.
 
 
 // The file runs a series of Media Source Entensions (MSE) operations on a
 // video tag.  The test takes several URL parameters described in
 //loadTestParams() function.
 
 (function() {
@@ skipping 357 matching lines @@
     function checkForCurrentTimeChange() {
       if (testDone)
         return;
 
       if (mediaElement.readyState < mediaElement.HAVE_METADATA ||
           mediaElement.currentTime <= 0) {
         listener = window.requestAnimationFrame(checkForCurrentTimeChange);
         return;
       }
 
+      var testEndTime = getPerfTimestamp();
       for (var i = 0; i < appenders.length; ++i) {
         appenders[i].onPlaybackStarted(mediaSource);
       }
 
-      var testEndTime = getPerfTimestamp();
-
       testDone = true;
       window.clearInterval(listener);
       window.clearTimeout(timeout);
 
       var stats = {};
       stats.total = testEndTime - testStartTime;
       stats.sourceOpen = mediaSourceOpenEndTime - mediaSourceOpenStartTime;
       stats.maxXHRLoadDuration = appenders[0].getXHRLoadDuration();
       stats.maxAppendDuration = appenders[0].getAppendDuration();
 
@@ skipping 126 matching lines @@
 
     if (testParams.doNotWaitForBodyOnLoad) {
       startTest();
     }
   }
 
   window["setupTest"] = setupTest;
   window.__testDone = false;
   window.__testMetrics = {};
 })();