Speed up long-running test cases.

test/mjsunit/harmony/symbols.js

 // Copyright 2013 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 327 matching lines @@
 
 function TestCachedKeyAfterScavenge() {
   gc();
   // Keyed property lookup are cached.  Hereby we assume that the keys are
   // tenured, so that we only have to clear the cache between mark compacts,
   // but not between scavenges.  This must also apply for symbol keys.
   var key = Symbol("key");
   var a = {};
   a[key] = "abc";
 
-  for (var i = 0; i < 1000000; i++) {
+  for (var i = 0; i < 100000; i++) {
     a[key] += "a";  // Allocations cause a scavenge.
   }
 }
 TestCachedKeyAfterScavenge();