Remove support for the keygen tag

third_party/WebKit/Source/core/css/themeWin.css

 /*
  * Copyright (C) 2008 Google Inc. All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  * 
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 79 matching lines @@
 
 input[type="search" i]::-webkit-search-results-decoration {
     margin: auto 3px auto 2px;
 }
 
 input[type="button" i], input[type="submit" i], input[type="reset" i], input[type="file" i]::-webkit-file-upload-button, button {
     padding: 1px 6px;
 }
 
 /* Windows selects are not rounded. Custom borders for them shouldn't be either. */
-keygen, 
 select, 
 select[size="0"],
 select[size="1"] {
     border-radius: 0;
     /* Same as native_theme_base. */
     border-color: #a9a9a9;
 }
 
 select[size],
 select[multiple],
 select[size][multiple] {
     /* Same as native_theme_base. */
     border: 1px solid #a9a9a9;
 }
 
 textarea {
     font-family: monospace;
     /* Same as native_theme_base. */
     border-color: #a9a9a9;
 }