Speed up tests for OSR of for-in and for-of loops.

R=marja@chromium.org
BUG=

Review URL: https://codereview.chromium.org/889293003

Cr-Commit-Position: refs/heads/master@{#26378}

test/mjsunit/compiler/osr-forin.js

@@ -16,7 +16,7 @@ function f(a) {
   return sum;
 }
 
-var a = new Array();
+var a = new Array(10000);
 for (var i = 0; i < 10000; i++) {
   a[i] = (i * 999) % 77;
 }

test/mjsunit/compiler/osr-forof.js

@@ -15,7 +15,7 @@ function f(a) {
   return sum;
 }
 
-var a = new Array();
+var a = new Array(10000);
 for (var i = 0; i < 10000; i++) {
   a[i] = (i * 999) % 77;
 }