Update heap test so it calls gc 6 times. This is necessary to avoid flakiness.

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/10668022

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11925 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/cctest/test-heap-profiler.cc

@@ -714,9 +714,9 @@ TEST(HeapSnapshotObjectsStats) {
   LocalContext env;
 
   v8::HeapProfiler::StartHeapObjectsTracking();
-  // We have to call GC 5 times. In other case the garbage will be
+  // We have to call GC 6 times. In other case the garbage will be
   // the reason of flakiness.
-  for (int i = 0; i < 5; ++i) {
+  for (int i = 0; i < 6; ++i) {
     HEAP->CollectAllGarbage(i::Heap::kNoGCFlags);
   }