如何删除没有属性的div标签; 在保持内在HTML的同时？

I'd like to use PHP DOM Document to remove div tags which do not contain any attributes. However, I'd like to be able to keep all inner HTML contents.

Example:

<div>
    <div>
        <div id="test">
            Testing...
        </div><!-- end #test -->
    </div>
</div>

Result:

<div id="test">
    Testing...
</div><!-- end #test -->

Here's what I was thinking, but can't seem to get this to do what I want. This method seems to be deleting everything instead of the <div> tags with no attributes.

# Remove blank div wraps
if ( $div_tags = $dom->getElementsByTagName( 'div' ) ) {

    $blank_divs = array();

    foreach ( $div_tags as $div_tag ) {

        if ( ! $div_tag->hasAttributes() ) {
            $blank_divs[] = $div_tag;
        }

    }

    if ( ! empty( $blank_divs ) ) {

        foreach ( array_reverse( $blank_divs ) as $blank_div ) {
            $blank_div->parentNode->removeChild( $blank_div );
        }

    }

}

If you know how many iterations you need to remove, you can do the following:

var icount = 2; // number of iterations.
for(i=0; i<icount; i++){
    var innerElement = $("#test").contents();
    $("#test").replaceWith(innerElement );
}

If you don't know your itterstion you just have to have an identifiable parent such as this:

<div id="container">
  <div>
    <div id="test">
        Testing...
    </div><!-- end #test -->
  </div>
</div>

<script>
  var innerElement = $("#test").contents();
  $("#container").replaceWith(innerElement );
</script>