Old and new about pages: simplify product logo animation code

chrome/browser/resources/help/help_content.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. */
 
 #about-container {
   align-items: center;
   display: flex;
 }
 
 #page-container #about-container {
   margin-top: 10px;
 }
 
 #product-description {
   -webkit-margin-start: 10px;
 }
 
-@-webkit-keyframes spin {
-  to { transform: rotate(-10turn); }
-}
-
-#product-logo.spin {
-  -webkit-animation: spin 500ms cubic-bezier(1, 0, 0, 1) forwards;
-}
-
 #version-container {
   margin-top: 30px;
 }
 
 #update-buttons-container {
   margin-top: 5px;
 }
 
 #update-status-container {
   margin-bottom: 12px;
@@ skipping 133 matching lines @@
 }
 
 #regulatory-label-container {
   padding-top: 32px;
 }
 
 #regulatory-label {
   display: block;
   width: 330px;
 }