title: Firefox not handling Applescript to select from drop down list same as Google Chrome
body: <p>I am using an Applescript to tab to and select an item from a dropdown box on a form, and return to the starting field. Using Firefox 57.0, both "Cakes, large" (the first item with the first letter "C") and "Cocktails" get selected.  Using Google Chrome 63.0 only "Cocktails" gets selected, which is what I want.  Any ideas how to get the desired result in Firefox?  </p>
  
  <p>Applescript:</p>
  
  <pre><code>tell application "System Events"
      tell application "System Events" to key code 48
      tell application "System Events" to key code 49
      keystroke "Cocktails"
      tell application "System Events" to key code 48 using shift down
      tell application "System Events" to key code 124 using command down
  end tell
  </code></pre>
  
  <p>HTML code:</p>
  
  <pre><code>&lt;div class="editor-field"&gt;
      &lt;select class="category-multi" id="RecipeTypes" multiple="multiple" name="RecipeTypes" style="display: none"&gt;&lt;option selected="selected" value="85"&gt;Fried doughs&lt;/option&gt;
  &lt;option selected="selected" value="64"&gt;Mousses, trifles, custards &amp;amp; creams&lt;/option&gt;
  &lt;/select&gt;    
      &lt;select class="form-control category-ddl" id="RecipeTypesDDL" name="RecipeTypesDDL"&gt;&lt;option value=""&gt;&lt;/option&gt;
  &lt;option value="41"&gt;Baked &amp;amp; steamed desserts&lt;/option&gt;
  &lt;option value="42"&gt;Beverages / drinks (no-alcohol)&lt;/option&gt;
  &lt;option value="82"&gt;Bread &amp;amp; buns, sweet&lt;/option&gt;
  &lt;option value="43"&gt;Bread &amp;amp; rolls, savory&lt;/option&gt;
  &lt;option value="44"&gt;Brownies, slices &amp;amp; bars&lt;/option&gt;
  &lt;option value="45"&gt;Cakes, large&lt;/option&gt;
  &lt;option value="46"&gt;Cakes, small&lt;/option&gt;
  &lt;option value="47"&gt;Candy / sweets&lt;/option&gt;
  &lt;option value="49"&gt;Cheesecakes&lt;/option&gt;
  &lt;option value="50"&gt;Children &amp;amp; baby food&lt;/option&gt;
  &lt;option value="51"&gt;Chili&lt;/option&gt;
  &lt;option value="52"&gt;Chutneys, pickles &amp;amp; relishes&lt;/option&gt;
  &lt;option value="53"&gt;Cocktails / drinks (with alcohol)&lt;/option&gt;
  &lt;option value="54"&gt;Cookies, biscuits &amp;amp; crackers&lt;/option&gt;
  &lt;option value="55"&gt;Crumbles, cobblers, crisps &amp;amp; bettys&lt;/option&gt;
  &lt;option value="56"&gt;Curry&lt;/option&gt;
  </code></pre>