Remove non-incremental idle notification handler.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index b465ca47c485bb7223cd3f6713dc230258b000fe..33d7bf4fecc66694c342ea48e65a5005dc9e3331 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -2062,9 +2062,6 @@ class Heap {
     return heap_size_mb / kMbPerMs;
   }
 
-  // Returns true if no more GC work is left.
-  bool IdleGlobalGC();
-
   void AdvanceIdleIncrementalMarking(intptr_t step_size);
 
   void ClearObjectStats(bool clear_last_time_stats = false);
@@ -2119,10 +2116,6 @@ class Heap {
 
   IncrementalMarking incremental_marking_;
 
-  int number_idle_notifications_;
-  unsigned int last_idle_notification_gc_count_;
-  bool last_idle_notification_gc_count_init_;
-
   int mark_sweeps_since_idle_round_started_;
   unsigned int gc_count_at_last_idle_gc_;
   int scavenges_since_last_idle_round_;