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

chrome/browser/resources/chromeos/login/screen_gaia_signin.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. */
 
 #gaia-signin {
   height: 528px;
   width: 448px;
 }
 
 #gaia-signin.full-width {
   padding: 44px 0 0;
   width: 562px;
 }
 
 .signin-link {
   color: rgb(37, 79, 155);
   cursor: pointer;
   text-decoration: none;
 }
 
 .signin-link:focus {
-  -webkit-transition: outline-color 200ms;
   /* Note: May use 1px solid here. */
   outline-color: rgb(77, 144, 254);
+  transition: outline-color 200ms;
 }
 
 #gaia-signin-form-container,
 #signin-frame {
   height: 100%;
   position: relative;
   width: 100%;
 }
 
 #signin-frame {
@@ skipping 65 matching lines @@
   right: 0;
   top: 0;
   z-index: 1;
 }
 
 .loading #gaia-navigation,
 .full-width #gaia-navigation {
   color: rgba(0, 0, 0, .54);
 }