applying patch from #387 - if map has changed size, destroy old tile, make a new one

git-svn-id: http://svn.openlayers.org/trunk/openlayers@1779 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/WMS/Untiled.js

@@ -150,6 +150,11 @@ OpenLayers.Layer.WMS.Untiled.prototype =
             var ul = new OpenLayers.LonLat(tileBounds.left, tileBounds.top);
             var pos = this.map.getLayerPxFromLonLat(ul);
 
+            if ( this.tile && !this.tile.size.equals(tileSize)) {
+                this.tile.destroy();
+                this.tile = null;
+            }
+
             if (!this.tile) {
                 this.tile = new OpenLayers.Tile.Image(this, pos, tileBounds, 
                                                      url, tileSize);