Tilemap.swap() called twice should not flip values

Repeat calls to swap() should not affect index values a second time.
"swap(1,2); swap(1,2)" should not be the same as "swap(2,1)."

(This also affects Phaser 1.1.6.)

src/tilemap/Tilemap.js

@@ -1157,7 +1157,7 @@ Phaser.Tilemap.prototype = {
         {
             this._results[index].index = this._tempB;
         }
-        else if (value.index === this._tempB)
+        if (value.index === this._tempB)
         {
             this._results[index].index = this._tempA;
         }