Correct F99 - keyCode is not an attribute (#4374)

Closes #4344

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Co-authored-by: Alastair Campbell <ac@alastc.com>
Co-authored-by: Kenneth G. Franqueiro <kfranqueiro@users.noreply.github.com>
Co-authored-by: Dan Bjorge <dan@dbjorge.net>
Co-authored-by: Mike Gower <mikegower@gmail.com>

Author: 5 people

techniques/failures/F99.html

@@ -31,7 +31,7 @@ <h2>Description</h2>
     <p>The test procedure suggests asking the author (often the developer of the site) whether keyboard shortcuts are used. If that information is trusted then the procedure can be simpler than pressing all the keys.</p>
 
     <p>The success criterion does not apply when single key shortcuts are only active when interface elements have the focus, for example, a <code class="language-html">select</code> element. Here, pressing a letter key is used for fast navigation within the select options.</p>
-    <p>Viewing page scripts and searching for typical keyboard event handlers like <code class="language-javascript">document.addEventListener('keydown' ...) </code> or the presence of the <code class="language-javascript">.keycode</code> attribute
+    <p>Viewing page scripts and searching for typical keyboard event handlers such as <code class="language-javascript">document.addEventListener('keydown' ...) </code> or the handling of keyboard-related event properties with code such as <code class="language-javascript">.key</code>, <code class="language-javascript">.code</code>, <code class="language-javascript">.charCode</code>, or <code class="language-javascript">.keyCode</code>
       may establish the presence of scripts that intercept keyboard shortcuts without modification keys like <kbd>ALT</kbd> or <kbd>Ctrl</kbd> being held down at the same time. As there are several ways of implementing character key events, this method is not considered reliable.</p>
     <p>Some browsers employ single key shortcuts with <kbd>Shift</kbd>. For example, Firefox opens a page search when pressing <kbd>Shift</kbd> + <kbd>/</kbd> and a search in page links when pressing <kbd><kbd>Shift</kbd> + <kbd>'</kbd></kbd>. In these cases, it will be necessary to press <kbd>Esc</kbd> or click an empty part of the page to remove the focus from the browser input.</p>
   </section>