Remove -webkit-*-before/after in:

chrome/browser/resources/chromeos/image_burner.css

 /* 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. */
 
 html,
 body,
 ul,
 li {
   margin: 0;
   padding: 0;
@@ skipping 50 matching lines @@
 p {
   margin-top: 0;
 }
 
 progress {
   margin-bottom: 0;
   width: 371px;
 }
 
 ul {
-  -webkit-margin-after: 25px;
-  -webkit-margin-before: 0;
+  margin-bottom: 25px;
+  margin-top: 0;
 }
 
 .aligned-to-start {
   -webkit-padding-start: 120px;
 }
 
 .float-start {
   float: left;
 }
 
@@ skipping 132 matching lines @@
 
 #main-content.success #warning-button,
 #main-content.warning-no-conf #warning-button,
 #main-content.device-detected-none #warning-button {
   display: none;
 }
 
 #main-content.error #warning-button {
   clear: both;
 }