title: OpenLayers getFeatureInfo popup generates this.size is null
body: <p>I am trying to create OpenLayers with popup feature info. I got the code from OpenLayers examples and only modified url to my local geoserver. The map is displaying, when i click on a feature the request is sent but the response is empty and firebug shows error "this.size is null". When i run the request url separately feature info is generated.
  Here is the code:</p>
  
  <pre><code>var map, info;
  
  function load() {
      map = new OpenLayers.Map({
          div: "map",
          maxExtent: new OpenLayers.Bounds(20.163,53.228,20.208,53.257)
          //maxExtent: new OpenLayers.Bounds(143.834,-43.648,148.479,-39.573)
          //maxExtent: new OpenLayers.Bounds(19,90,19,90)
      });
  
      var punkty_zdjecia = new OpenLayers.Layer.WMS("Punkty Zdjecia",
          "http://localhost:6060/geoserver/wms", 
          {'layers': 'cite:ulice2', transparent: false, format: 'image/gif'},
          {isBaseLayer: true}
      );
  
      map.addLayers([punkty_zdjecia]); 
  
      info = new OpenLayers.Control.WMSGetFeatureInfo({
          url: 'http://localhost:6060/geoserver/wms', 
          title: 'Test url',
          queryVisible: true,
          eventListeners: {
              getfeatureinfo: function(event) {
                  map.addPopup(new OpenLayers.Popup.FramedCloud(
                      "chicken", 
                      map.getLonLatFromPixel(event.xy),
                      new OpenLayers.Size(200,200),
                      event.text,
                      null,
                      true
                  ));
              }
          }
      });
      map.addControl(info);
      info.activate();
  
      map.addControl(new OpenLayers.Control.LayerSwitcher());
      map.zoomToMaxExtent();
  }
  </code></pre>
  
  <p>
    </p>
  
  <p></p>
  
  <p>I am using OpenLayers 2.11 and Firefox browser</p>