Revert r4029.

Review URL: http://codereview.chromium.org/668153

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4037 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap.cc

@@ -3081,7 +3081,7 @@ bool Heap::IdleNotification() {
   static int number_idle_notifications = 0;
   static int last_gc_count = gc_count_;
 
-  if (contexts_disposed_ > 0) {
+  if (!FLAG_expose_gc && (contexts_disposed_ > 0)) {
     HistogramTimerScope scope(&Counters::gc_context);
     CollectAllGarbage(false);
     ASSERT(contexts_disposed_ == 0);