Cast zoom level to integer. r=pgiraud (closes #2180)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@9955 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -1664,7 +1664,7 @@ OpenLayers.Map = OpenLayers.Class({
             }
 
             if (zoomChanged) {
-                this.zoom = zoom;
+                this.zoom = parseInt(zoom);
                 this.resolution = this.getResolutionForZoom(zoom);
                 // zoom level has changed, increment viewRequestID.
                 this.viewRequestID++;