title: Bootstrap data-trigger="focus" doesn't work
body: <p>I have a Bootstrap popover defined on an icon which works fine if I do not have data-trigger="focus" as part of its definition.  When I include that, the popover does not display when I click the icon.  Here's the code without the data-trigger.</p>
  
  <pre><code>&lt;a data-toggle="popover" data-placement="left" data-title="Membership history for Fred Smith" data-html="true" data-content="&lt;table&gt;&lt;thead&gt;&lt;tr&gt;&lt;th class='col-md-2 text-left'&gt;Renewed&lt;/th&gt;&lt;th&gt;Expiration&lt;/th&gt;&lt;th&gt;Type&lt;/th&gt;&lt;/tr&gt;&lt;/thead&gt;&lt;tbody&gt;&lt;tr&gt;&lt;td&gt;12/09/2016&lt;/td&gt;&lt;td&gt;12/31/2017&lt;/td&gt;&lt;td&gt;1-Year Individual&lt;/td&gt;&lt;/tr&gt;&lt;/tbody&gt;&lt;/table&gt;"&gt;&lt;span class="glyphicon glyphicon-info-sign" style="color:grey;"&gt;&lt;/span&gt;&lt;/a&gt;
  </code></pre>
  
  <p>And the code including the data-trigger:</p>
  
  <pre><code>&lt;a data-toggle="popover" data-placement="left" data-trigger="focus" data-title="Membership history for Fred Smith" data-html="true" data-content="&lt;table&gt;&lt;thead&gt;&lt;tr&gt;&lt;th class='col-md-2 text-left'&gt;Renewed&lt;/th&gt;&lt;th&gt;Expiration&lt;/th&gt;&lt;th&gt;Type&lt;/th&gt;&lt;/tr&gt;&lt;/thead&gt;&lt;tbody&gt;&lt;tr&gt;&lt;td&gt;12/09/2016&lt;/td&gt;&lt;td&gt;12/31/2017&lt;/td&gt;&lt;td&gt;1-Year Individual&lt;/td&gt;&lt;/tr&gt;&lt;/tbody&gt;&lt;/table&gt;"&gt;&lt;span class="glyphicon glyphicon-info-sign" style="color:grey;"&gt;&lt;/span&gt;&lt;/a&gt;
  </code></pre>
  
  <p>I should also mention that the icon is within a table cell.</p>
  
  <p>Any ideas?</p>