Drop the -webkit prefix from user-select CSS rule in ui/.

ui/webui/resources/css/tree.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. */
 
 tree {
   display: block;
   outline: none;
   overflow: auto;
 }
 
 .tree-item > .tree-row {
-  -webkit-user-select: none;
   background-color: rgba(255, 255, 255, 0);
   border: 1px solid rgba(255, 255, 255, 0); /* transparent white */
   border-radius: 2px;
   color: black;
   cursor: default;
   line-height: 28px;
   padding: 0 3px;
   position: relative;
+  user-select: none;
   white-space: nowrap;
 }
 
 .expand-icon {
   transform: rotate(-90deg);
   -webkit-transition: all 150ms;
   background: url(../images/tree_triangle.svg) no-repeat center center;
   background-size: 8px 5px;
   display: inline-block;
   height: 16px;
@@ skipping 114 matching lines @@
 }
 
 /* We need to ensure that even empty labels take up space */
 .tree-label:empty::after {
   content: ' ';
   white-space: pre;
 }
 
 .tree-rename > .tree-row > .tree-label {
   -webkit-user-modify: read-write-plaintext-only;
-  -webkit-user-select: auto;
   background: white;
   color: black;
   outline: 1px solid black;
+  user-select: auto;
 }
 
 .tree-item[editing] input {
   /* Do not inherit the line-height */
   font-family: inherit;
   font-size: inherit;
   font-weight: inherit;
   margin: -2px -8px -2px -3px;
 <if expr="not is_macosx and not is_ios">
   outline: none;
 </if>
   padding: 1px 7px 1px 1px;
 }
 
 html[dir=rtl] .tree-item[editing] input {
   margin: -2px -3px -2px -8px;
   padding: 1px 1px 1px 7px;
 }