Ensuring that setVisibility is called during setBaseLayer for layers where visibility is true. (With allOverlays true, a layer doesn't have to be visible to beocome the base layer - twisted huh?) r=ahocevar (closes #2290)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10023 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -1122,7 +1122,7 @@ OpenLayers.Map = OpenLayers.Class({
                 // changing. This is used by tiles to check if they should 
                 // draw themselves.
                 this.viewRequestID++;
-                if(!this.allOverlays) {
+                if(!this.allOverlays || this.baseLayer.visibility) {
                     this.baseLayer.setVisibility(true);
                 }