Activate HiDPI support in wms-tiled example

examples/wms-tiled.js

@@ -11,11 +11,12 @@ var layers = [
     source: new ol.source.MapQuest({layer: 'sat'})
   }),
   new ol.layer.Tile({
-    source: new ol.source.TileWMS({
+    source: new ol.source.TileWMS(/** @type {olx.source.TileWMSOptions} */ ({
       url: 'http://demo.opengeo.org/geoserver/wms',
       params: {'LAYERS': 'topp:states', 'TILED': true},
-      extent: [-13884991, 2870341, -7455066, 6338219]
-    })
+      extent: [-13884991, 2870341, -7455066, 6338219],
+      serverType: 'geoserver'
+    }))
   })
 ];
 var map = new ol.Map({