Cut down memory usage of array-functions-prototype-misc.js by 10x

It used to require >1GB of memory which leads to flaky test failures on
machines with less memory when executing multiple variants in parallel

R=cbruni@chromium.org,ulan@chromium.org
BUG=v8:5706

Change-Id: Id8c6f49cbfa51f2d443991c1493f225810efb18f
Reviewed-on: https://chromium-review.googlesource.com/439310
Commit-Queue: Camillo Bruni <cbruni@google.com>
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43038}

test/mjsunit/array-functions-prototype-misc.js

@@ -31,7 +31,7 @@
  * should work on other objects too, so we test that too.
  */
 
-var LARGE = 4000000;
+var LARGE = 400000;
 var VERYLARGE = 4000000000;
 
 // Nicer for firefox 1.5.  Unless you uncomment the following two lines,