Fix for trac ticket # 3554 single-arg Map constructor does not work if you pass a DOM element ref

-- Hopefully now I got it right. This uses Util.isElement() --

Here is the text of the original ticket at http://trac.osgeo.org/openlayers/ticket/3554

The docs for OpenLayers.Map indicate that you can pass a DOM element into the single-arg constructor. You can verify that it doesn't work with:
```html
<html>
	<body>
  	<div id="mapdiv"></div>

  	<script src="http://www.openlayers.org/api/OpenLayers.js"></script>

  	<script type="text/javascript">
		function Map(element) {
	    	var map = new OpenLayers.Map(element);
			map.addLayer(new OpenLayers.Layer.OSM());
			map.zoomToMaxExtent();
		}

		var mapContainer = document.getElementById('mapdiv');
		var map = new Map(mapContainer);
  	</script>
	</body>
</html>
```
You can workaround this problem, by replacing the last line above with:

    var map = new Map({div: mapContainer});

I have written a test that replicates the bug and applied the patch at:

http://trac.osgeo.org/openlayers/attachment/ticket/3554/openlayers-3554.patch

For any original code that I have added, I am the author/copyright holder of this code and am dedicating it to the public domain under the terms at http://creativecommons.org/publicdomain/zero/1.0/.