Porting r9605 to x64 (elements kind conversion in generated code).

test/mjsunit/elements-transition.js

Index: test/mjsunit/elements-transition.js
diff --git a/test/mjsunit/elements-transition.js b/test/mjsunit/elements-transition.js
index f1983243374a4a2c4114c5bed4800e87ebe08eb1..ab3c69022932a9bc7e17ad33a2e3864c67137790 100644
--- a/test/mjsunit/elements-transition.js
+++ b/test/mjsunit/elements-transition.js
@@ -69,6 +69,9 @@ if (support_smi_only_arrays) {
         assertEquals(2*i+1, array_2[i]);
       }
     }
+
+    assertEquals(length, array_1.length);
+    assertEquals(length, array_2.length);
   }
 
   test(false, false, function(a,i,v){ a[i] = v; }, 100);