Fix conflated prototype chains when extending.

Author: pkaminski

src/core.js

@@ -48,7 +48,7 @@ var CryptoJS = CryptoJS || (function (Math, undefined) {
                 }
 
                 // Create default initializer
-                if (!subtype.hasOwnProperty('init')) {
+                if (!subtype.hasOwnProperty('init') || this.init === subtype.init) {
                     subtype.init = function () {
                         subtype.$super.init.apply(this, arguments);
                     };

test/lib-base-test.js

@@ -81,6 +81,12 @@ YUI.add('lib-base-test', function (Y) {
             this.data.obj.initArg = 'newValue';
 
             Y.Assert.areNotEqual(this.data.obj.initArg, this.data.objClone.initArg);
+        },
+
+        testCloneLeavesOriginalInitPrototypeUnchanged: function() {
+            Y.Assert.areEqual(this.data.obj, this.data.obj.init.prototype);
+            Y.Assert.areEqual(this.data.objClone, this.data.objClone.init.prototype);
+            Y.Assert.areNotEqual(this.data.obj.init.prototype, this.data.objClone.init.prototype);
         }
     }));
 }, '$Rev$');