Fixed an issue with sparse arrays when shortening the array where the…

… collection of keys is modified while removing keys.

Src/IronJS.Runtime/Objects/ArrayObject.cs

@@ -438,7 +438,7 @@ public void PutLength(uint newLength, uint length)
                     return;
                 }
 
-                foreach (var key in this.storage.Keys)
+                foreach (var key in this.storage.Keys.ToList())
                 {
                     if (key >= newLength)
                         this.storage.Remove(key);