Switch to using '-t ios' for grit

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;
 }
 
@@ skipping 151 matching lines @@
   color: black;
   outline: 1px solid black;
 }
 
 .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">
+<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;
 }