[ChromeOS] Reland - Make WebUI login use only needed resources.

chrome/browser/resources/chromeos/login/screen_gaia_signin.css

 /* Copyright (c) 2011 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.
  */
 
-#signin {
-  -webkit-box-align: center;
-  -webkit-box-pack: center;
-  display: -webkit-box;
-  overflow: hidden;
-}
-
 #gaia-signin {
   -webkit-box-align: center;
   -webkit-box-pack: center;
   display: -webkit-box;
   height: 470px;
 }
 
 #signin-right {
   font-size: 12px;
   position: absolute;
@@ skipping 31 matching lines @@
 #gaia-loading {
   -webkit-box-align: center;
   -webkit-box-pack: center;
   bottom: 0;
   display: -webkit-box;
   left: 0;
   position: absolute;
   right: 0;
   top: 0;
 }
-
-#email,
-#password {
-  display: block;
-  margin-bottom: 20px;
-}