title: KML/OpenLayers GroundOverlay element that doesn't have <Document> tags not loading onto map?
body: <p>I have a KML element with no document tags and just  tags like...(with some irrelevant elements removed with ...) </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;kml xmlns="http://www.opengis.net/kml/2.2"&gt;
  &lt;GroundOverlay&gt;
      &lt;name&gt;...&lt;/name&gt;
      &lt;description&gt;...&lt;/description&gt;
      &lt;Icon&gt;&lt;href&gt;...&lt;/href&gt;&lt;/Icon&gt;
      &lt;LatLonBox&gt;
         ...
      &lt;/LatLonBox&gt;
  &lt;/GroundOverlay&gt;
  &lt;/kml&gt;
  </code></pre>
  
  <p>In OpenLayers, I can't get this to load without document tags around the GroundOverlay. I can however get a place mark that is the root node with no document tags to load fine. </p>
  
  <p>Is there a way to a KML with a GroundOverlay root node into KML that doesn't have document tags? It seems to load fine in other renderers like Google Earth and Cesium. </p>