AX: Make picker indicator elements focusable if accessibility is enabled.

Source/core/css/html.css

 /*
  * The default style sheet used to render HTML.
  *
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 705 matching lines @@
     padding: 0.17em 0.34em;
     -webkit-user-modify: read-only !important;
     opacity: 0;
     pointer-events: none;
 }
 
 input::-webkit-calendar-picker-indicator:hover {
     background-color: #eee;
 }
 
-input:enabled:read-write:-webkit-any(:focus,:hover)::-webkit-calendar-picker-indicator {
+input:enabled:read-write:-webkit-any(:focus,:hover)::-webkit-calendar-picker-indicator,
+input::-webkit-calendar-picker-indicator:focus {
     opacity: 1;
     pointer-events: auto;
 }
 
 input[type="date" i]:disabled::-webkit-clear-button,
 input[type="date" i]:disabled::-webkit-inner-spin-button,
 input[type="datetime-local" i]:disabled::-webkit-clear-button,
 input[type="datetime-local" i]:disabled::-webkit-inner-spin-button,
 input[type="month" i]:disabled::-webkit-clear-button,
 input[type="month" i]:disabled::-webkit-inner-spin-button,
@@ skipping 351 matching lines @@
 @page {
     /* FIXME: Define the right default values for page properties. */
     size: auto;
     margin: auto;
     padding: 0px;
     border-width: 0px;
 }
 
 /* noscript is handled internally, as it depends on settings. */