[heap] New heuristics for starting of incremental marking.

src/heap/incremental-marking.h

Index: src/heap/incremental-marking.h
diff --git a/src/heap/incremental-marking.h b/src/heap/incremental-marking.h
index 8990d0f3f14e5886fb167a51b629a0e9cde5756d..c2290c4d8206ee39907d7d327baca35cb9e5db46 100644
--- a/src/heap/incremental-marking.h
+++ b/src/heap/incremental-marking.h
@@ -72,8 +72,6 @@ class IncrementalMarking {
 
   bool CanBeActivated();
 
-  bool ShouldActivateEvenWithoutIdleNotification();
-
   bool WasActivated();
 
   void Start(GarbageCollectionReason gc_reason);
@@ -117,6 +115,12 @@ class IncrementalMarking {
   // incremental marking to be postponed.
   static const int kMaxIdleMarkingDelayCounter = 3;
 
+#ifndef DEBUG
+  static const intptr_t kActivationThreshold = 8 * MB;
+#else
+  static const intptr_t kActivationThreshold = 0;
+#endif
+
   void FinalizeSweeping();
 
   size_t Step(size_t bytes_to_process, CompletionAction action,