webui: make 0 into 0ms when it's a <time>.

ui/webui/resources/css/overlay.css

 /* Copyright (c) 2012 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 shield that overlays the background. */
 .overlay {
   -webkit-box-align: center;
   -webkit-box-orient: vertical;
   -webkit-box-pack: center;
   /* TODO(dbeam): remove perspective when http://crbug.com/374970 is fixed. */
@@ skipping 28 matching lines @@
   display: -webkit-box;
   min-width: 400px;
   padding: 0;
   position: relative;
   z-index: 0;
 }
 
 /* If the options page is loading don't do the transition. */
 .loading .overlay,
 .loading .overlay .page {
-  -webkit-transition-duration: 0 !important;
+  -webkit-transition-duration: 0ms !important;
 }
 
 /* keyframes used to pulse the overlay */
 @-webkit-keyframes pulse {
  0% {
    -webkit-transform: scale(1);
  }
  40% {
    -webkit-transform: scale(1.02);
   }
@@ skipping 134 matching lines @@
 #overlay-container-1 {
   z-index: 11;
 }
 #overlay-container-2 {
   z-index: 12;
 }
 
 .transparent {
   opacity: 0;
 }