webui: minimize webui flicker.

chrome/browser/resources/history/history_mobile.css

 /* Copyright (c) 2013 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. */
 
 /* This file contains styles specific to Android and iOS. */
 
 html {
   height: 100%;
 }
 
 body {
   color: rgb(76, 76, 76);
+  font-size: initial;
   height: 100%;
   margin: 0;
 }
 
 .page {
   -webkit-flex-flow: column;
   display: -webkit-flex;
   height: 100%;
 }
 
@@ skipping 285 matching lines @@
 <if expr="is_ios">
 .ios-keyboard-visible #clear-browsing-data {
   display: none;
 }
 
 .ios-keyboard-visible #scrolling-container {
   /* Should be 0, but that breaks scrolling -- see crbug.com/292715. */
   bottom: -1px;
 }
 </if> /* is_ios */