ChromeOS: Fix material design OOBE dialog alignment.

ui/login/screen_container.css

 /* Copyright 2014 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.
  */
 
 #outer-container {
   -webkit-box-align: center;
   -webkit-box-pack: center;
   -webkit-perspective: 1px; /* Workaround, see http://crbug.com/360567 */
   bottom: 57px;  /* Leave space for the header bar */
@@ skipping 102 matching lines @@
 }
 
 #oobe:not([md-mode]) #step-logo {
   -webkit-margin-start: 17px;
   display: -webkit-box;
   position: absolute;
   top: 15px;
 }
 
 #oobe[md-mode] #step-logo {
-  visibility: hidden;
+  display: none;
 }
 
 #progress-dots {
   -webkit-box-pack: center;
   -webkit-transition: opacity 200ms ease-in-out,
                       visibility 200ms ease-in-out;
   display: -webkit-box;
   margin-top: 15px;
 }
 
@@ skipping 98 matching lines @@
   line-height: 31px;
   text-transform: lowercase;
   width: 23em;
 }
 
 .header-section::before {
   /* Divider in header between product name and title,
    * like "[Product name] > [step header]". */
   content: '\00A0\203A\00A0\00A0';
 }