only draw the layer when it needs to be drawn

git-svn-id: http://svn.openlayers.org/trunk/openlayers@1625 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -281,20 +281,19 @@ OpenLayers.Map.prototype = {
         this.layers.push(layer);
         layer.setMap(this);
 
-        //make sure layer draws itself!
+        if (layer.isBaseLayer)  {
-        if (this.center != null) {
-            var bounds = this.getExtent();
-            layer.moveTo(bounds, true);
-        }
-
-        if (layer.isBaseLayer) {
-            // set the first baselaye we add as the baselayer
             if (this.baseLayer == null) {
+                // set the first baselaye we add as the baselayer
                 this.setBaseLayer(layer);
                 this.events.triggerEvent("changebaselayer");
             } else {
                 layer.setVisibility(false);
             }
+        } else {
+            var extent = this.getExtent();
+            if (extent) {
+                layer.moveTo(extent, true);   
+            }
         }
 
         this.events.triggerEvent("addlayer");