Avoid double initialization of arrays.

test/mjsunit/regress/regress-121407.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 19 matching lines @@
 a.length=2000;
 for (var i = 0; i <= 256; i++) {
     a[i] = new Object();
 }
 
 a = [0.5,1.5,2.5,3.5,4.5,5.5];
 a[2000000] = 2000000;
 a.length=2000;
 for (var i = 0; i <= 256; i++) {
     a[i] = new Object();
-}
+}