Limit rate of full garbage collections triggered by idle notification.

src/heap/mark-compact.h

Index: src/heap/mark-compact.h
diff --git a/src/heap/mark-compact.h b/src/heap/mark-compact.h
index ddb993f5a2f676491e732da2a1a39cae26c48b59..3aff29c177a155469118255d150320908f808c42 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -684,6 +684,8 @@ class MarkCompactCollector {
   bool IsSlotInLiveObject(HeapObject** address, HeapObject* object);
   void VerifyIsSlotInLiveObject(HeapObject** address, HeapObject* object);
 
+  size_t last_mark_compact_time() const { return last_mark_compact_time_; }
+
  private:
   class SweeperTask;
 
@@ -910,6 +912,8 @@ class MarkCompactCollector {
   SmartPointer<FreeList> free_list_old_data_space_;
   SmartPointer<FreeList> free_list_old_pointer_space_;
 
+  size_t last_mark_compact_time_;
+
   friend class Heap;
 };