Remove webkit prefixes for CSS Animation in ui/ styles

ui/file_manager/file_manager/foreground/elements/files_metadata_entry.html

 <!-- Copyright 2016 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.
 -->
 
 <link rel="import" href="chrome://resources/polymer/v1_0/polymer/polymer.html">
 
 <dom-module id="files-metadata-entry">
   <style>
     div {
@@ skipping 30 matching lines @@
       overflow-wrap: break-word;
       vertical-align: bottom;
       width: 128px;
     }
 
     #value[loading] {
       font-size: 30px;
     }
 
     #value[loading]:after {
-      -webkit-animation: ellipsis steps(4,end) 900ms infinite;
       animation: ellipsis steps(4,end) 900ms infinite;
       content: "\2026"; /* ascii code for the ellipsis character */
       display: inline-block;
       overflow: hidden;
       vertical-align: bottom;
       width: 0px;
     }
 
     @keyframes ellipsis {
       to {
         width: 1.25em;
       }
     }
 
-    @-webkit-keyframes ellipsis {
+    @keyframes ellipsis {
       to {
         width: 1.25em;
       }
     }
   </style>
   <template>
     <div id="box" hidden="[[!value]]">
       <div id="padding"></div>
       <div id="key">[[key]]</div>
       <div id="value" loading$="{{loading}}"><div hidden="[[loading]]">[[value]]</div></div>
     </div>
   </template>
 </dom-module>
 
 <script src="files_metadata_entry.js"></script>