[web_dev_style] Changing :pseudo-element to ::pseudo-element to match

chrome/browser/resources/shared/css/table.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. */
 
 html.col-resize * {
   cursor: col-resize !important;
 }
 
 .table[hasElementFocus] > list > [lead] {
   border-color: hsl(214, 91%, 65%);
@@ skipping 70 matching lines @@
   margin: 0 7px;
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
 }
 
 .table-header-label > * {
   padding: 0 12px;
 }
 
-.table-header-sort-image-desc:after {
+.table-header-sort-image-desc::after {
   -webkit-padding-start: 5px;
   color: #888;
   content: '\25be'; /* BLACK DOWN-POINTING SMALL TRIANGLE */
   position: relative;
   top: -2px;
 }
 
-.table-header-sort-image-asc:after {
+.table-header-sort-image-asc::after {
   -webkit-padding-start: 5px;
   color: #888;
   content: '\25b4'; /* BLACK UP-POINTING SMALL TRIANGLE */
   position: relative;
   top: -2px;
 }
 
 .table-header-splitter {
   -webkit-margin-start: -1px;
   background-color: black;
   cursor: col-resize;
   height: 100%;
   left: 0;
   position: absolute;
   top: 0;
   width: 5px;
 }