Reduce usage of webkit CSS prefixes in chrome/browser/resources

chrome/browser/resources/chromeos/first_run/first_run.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.
 
 /**
  * @fileoverview First run UI.
  */
 
 // <include src="step.js">
 
 // Transitions durations.
 /** @const  */ var DEFAULT_TRANSITION_DURATION_MS = 400;
 /** @const  */ var BG_TRANSITION_DURATION_MS = 800;
 
 /**
  * Changes visibility of element with animated transition.
  * @param {Element} element Element which visibility should be changed.
  * @param {boolean} visible Whether element should be visible after transition.
  * @param {number=} opt_transitionDuration Time length of transition in
  *     milliseconds. Default value is DEFAULT_TRANSITION_DURATION_MS.
  * @param {function()=} opt_onFinished Called after transition has finished.
  */
 function changeVisibility(
     element, visible, opt_transitionDuration, opt_onFinished) {

[Dan Beam, 2017/02/13 06:24:39]

i'm fairly sure that something in this method is blowing up the firstrun tests

   var classes = element.classList;
   // If target visibility is the same as current element visibility.
   if (classes.contains('transparent') === !visible) {
     if (opt_onFinished)
       opt_onFinished();
     return;
   }
   var transitionDuration = (opt_transitionDuration === undefined) ?
     cr.FirstRun.getDefaultTransitionDuration() : opt_transitionDuration;
   var style = element.style;
   var oldDurationValue = style.getPropertyValue('transition-duration');
   style.setProperty('transition-duration', transitionDuration + 'ms');
   var transition = visible ? 'show-animated' : 'hide-animated';
   classes.add(transition);
   classes.toggle('transparent');
-  element.addEventListener('webkitTransitionEnd', function f() {
-    element.removeEventListener('webkitTransitionEnd', f);
+  element.addEventListener('transitionend', function f() {
+    element.removeEventListener('transitionend', f);
     classes.remove(transition);
     if (oldDurationValue)
       style.setProperty('transition-duration', oldDurationValue);
     else
       style.removeProperty('transition-duration');
     if (opt_onFinished)
       opt_onFinished();
   });
   ensureTransitionEndEvent(element, transitionDuration);
 }
@@ skipping 218 matching lines @@
     }
   };
 });
 
 /**
  * Initializes UI.
  */
 window.onload = function() {
   cr.FirstRun.initialize();
 };