Turn on linter on html generated by transclusions

Change-Id: I0120efef419ff31828b15bcce5b03804fe1a93f6
Some fastidious cleanup in the dom linter

 * Also, prevent a case where a template group won't be cleared because
   the last node is skipped as fostered content. Ex:

     <table>
     {{echo|<div>hi</div><div>ho</div>}}
     <tr>
     <td>hello</td>
     </tr>
     </table>

Change-Id: I8e697b6daf93b57124f6acb98d5774e3a6c1a3cb
Merge "Turn on linter on html generated by transclusions"
Merge "Some fastidious cleanup in the dom linter"