Enhance the HTML form element to support containers to enclose form elements.

The HTML form element allows insertion of arbitrary HTML, but appears to not support the HTML container elements such as <a>,<div>,<fieldset> that allow phrasing, flow and transparent content.  A simple way to do this is to not automatically provide the end-tag (e.g. </div> or </fieldset>) in the opening HTML element.  The developer would have to add an ending HTML element with the end-tag after the enclosed form elements.  A more comprehensive approach would be to combine container support with form block construction.