extra null check on output to match rectangle

Author: beeglebug

src/geom/Circle.js

@@ -140,7 +140,7 @@ Phaser.Circle.prototype = {
     */
     clone: function (output) {
 
-        if (typeof output === "undefined")
+        if (typeof output === "undefined" || output === null)
         {
             output = new Phaser.Circle(this.x, this.y, this.diameter);
         }

src/geom/Ellipse.js

@@ -106,7 +106,7 @@ Phaser.Ellipse.prototype = {
     */
     clone: function(output) {
 
-        if (typeof output === "undefined")
+        if (typeof output === "undefined" || output === null)
         {
             output = new Phaser.Ellipse(this.x, this.y, this.width, this.height);
         }

src/geom/Point.js

@@ -222,7 +222,7 @@ Phaser.Point.prototype = {
     */
     clone: function (output) {
 
-        if (typeof output === "undefined")
+        if (typeof output === "undefined" || output === null)
         {
             output = new Phaser.Point(this.x, this.y);
         }