Faster moving FixedArray elements around.

src/array.js

Index: src/array.js
diff --git a/src/array.js b/src/array.js
index c28a662982ca2171c5af842ebf6eca0ba8190907..e33c2809ce63abfbc6f5403ff58700bdc9acb657 100644
--- a/src/array.js
+++ b/src/array.js
@@ -1149,6 +1149,8 @@ function SetupArray() {
     ArrayReduce: 1,
     ArrayReduceRight: 1
   });
+
+  %FinishArrayPrototypeSetup($Array.prototype);
 }