Remove support for the obsolete <isindex> tag.

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 372 matching lines @@
     -webkit-padding-after: 0.625em;
     border: 2px groove ThreeDFace;
     min-width: -webkit-min-content;
 }
 
 button {
     -webkit-appearance: button;
 }
 
 /* Form controls don't go vertical. */
-input, textarea, keygen, select, button, isindex, meter, progress {
+input, textarea, keygen, select, button, meter, progress {
     -webkit-writing-mode: horizontal-tb !important;
 }
 
-input, textarea, keygen, select, button, isindex {
+input, textarea, keygen, select, button {
     margin: 0__qem;
     font: -webkit-small-control;
     color: initial;
     letter-spacing: normal;
     word-spacing: normal;
     line-height: normal;
     text-transform: none;
     text-indent: 0;
     text-shadow: none;
     display: inline-block;
     text-align: start;
 }
 
 input[type="hidden"] {
     display: none
 }
 
-input, input[type="password"], input[type="search"], isindex {
+input, input[type="password"], input[type="search"] {
     -webkit-appearance: textfield;
     padding: 1px;
     background-color: white;
     border: 2px inset;
     -webkit-rtl-ordering: logical;
     -webkit-user-select: text;
     cursor: auto;
 }
 
 input[type="search"] {
@@ skipping 229 matching lines @@
     word-wrap: break-word;
 }
 
 ::-webkit-input-placeholder {
     -webkit-text-security: none;
     color: darkGray;
     display: block !important;
     pointer-events: none !important;
 }
 
-input::-webkit-input-placeholder, isindex::-webkit-input-placeholder {
+input::-webkit-input-placeholder {
     white-space: pre;
     word-wrap: normal;
     overflow: hidden;
     -webkit-user-modify: read-only !important;
 }
 
 input[type="password"] {
     -webkit-text-security: disc !important;
 }
 
@@ skipping 380 matching lines @@
 
 /* Read-only text fields do not show a focus ring but do still receive focus */
 html:focus, body:focus, input[readonly]:focus { 
     outline: none
 }
 
 applet:focus, embed:focus, iframe:focus, object:focus {
     outline: none
 }
   
-input:focus, textarea:focus, isindex:focus, keygen:focus, select:focus {
+input:focus, textarea:focus, keygen:focus, select:focus {
     outline-offset: -2px
 }
 
 input[type="button"]:focus,
 input[type="checkbox"]:focus,
 input[type="file"]:focus,
 input[type="hidden"]:focus,
 input[type="image"]:focus,
 input[type="radio"]:focus,
 input[type="reset"]:focus,
@@ skipping 88 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. */