permit abstract classes (an abstract class being a class without an "initialize" method) as parent classes, final patch from tschaub, r=tschaub (closes #1987)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@9091 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/BaseTypes/Class.js

@@ -41,19 +41,17 @@ OpenLayers.Class = function() {
             // make the class passed as the first argument the superclass
             if(i == 0 && len > 1) {
                 initialize = arguments[i].prototype.initialize;
-                if(typeof initialize === "function") {
-                    // replace the initialize method with an empty function,
-                    // because we do not want to create a real instance here
-                    arguments[i].prototype.initialize = function() {};
-                    // the line below makes sure that the new class has a
-                    // superclass
-                    extended = new arguments[i];
-                    // restore the original initialize method
-                    arguments[i].prototype.initialize = initialize;
+                // replace the initialize method with an empty function,
+                // because we do not want to create a real instance here
+                arguments[i].prototype.initialize = function() {};
+                // the line below makes sure that the new class has a
+                // superclass
+                extended = new arguments[i];
+                // restore the original initialize method
+                if(initialize === undefined) {
+                    delete arguments[i].prototype.initialize;
                 } else {
-                    // if someone uses Class to mix objects, we don't want to
-                    // mess with the prototype
-                    extended = new arguments[i];
+                    arguments[i].prototype.initialize = initialize;
                 }
             }
             // get the prototype of the superclass