prevent firefox tab going to scrollable listbox as it disappears

Author: smhigley

examples/combobox/combobox-select-only.html

@@ -55,7 +55,7 @@ <h2 id="ex_label">Example</h2>
                 tabindex="0"
                 >
             </div>
-            <div class="combo-menu" role="listbox" id="listbox1">
+            <div class="combo-menu" role="listbox" id="listbox1" tabindex="-1">
                 <!-- options are inserted here -->
                 <!-- e.g. <div role="option" id="op1">option text</div>  -->
             </div>
@@ -276,7 +276,7 @@ <h3 id="rps_label_combobox">Combobox</h3>
             </th>
             <td></td>
             <td><code>div</code></td>
-            <td>Identifies the input as a combobox.</td>
+            <td>Identifies the element as a combobox.</td>
           </tr>
           <tr data-test-id="combobox-aria-labelledby">
             <td></td>
@@ -320,7 +320,7 @@ <h3 id="rps_label_combobox">Combobox</h3>
               <ul>
                 <li>When an option in the listbox is visually indicated as having keyboard focus, refers to that option.</li>
                 <li>When navigation keys, such as <kbd>Down Arrow</kbd>, are pressed, the JavaScript changes the value.</li>
-                <li>Enables assistive technologies to know which element the application regards as focused while DOM focus remains on the <code>input</code> element.</li>
+                <li>Enables assistive technologies to know which element the application regards as focused while DOM focus remains on the <code>combobox</code> element.</li>
                 <li>
                   For more information about this focus management technique, see
                   <a href="../../#kbd_focus_activedescendant">Using aria-activedescendant to Manage Focus.</a>

examples/combobox/js/select-only.js

@@ -326,8 +326,7 @@ Select.prototype.selectOption = function(index) {
   this.activeIndex = index;
 
   // update displayed value
-  const selected = this.options[index];
-  this.comboEl.innerHTML = selected;
+  this.comboEl.innerHTML = this.options[index];;
 
   // update aria-selected
   const options = this.el.querySelectorAll('[role=option]');