[heap] Simplify heuristics for incremental step size.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index e0d20a032fb87bf97848b38402246b36529d9685..c7adefc4f1978972475075a5091882d285528bbb 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -1677,10 +1677,6 @@ class Heap {
   // Flush the number to string cache.
   void FlushNumberStringCache();
 
-  // TODO(hpayer): Allocation site pretenuring may make this method obsolete.
-  // Re-visit incremental marking heuristics.
-  bool IsHighSurvivalRate() { return high_survival_rate_period_length_ > 0; }
-
   void ConfigureInitialOldGenerationSize();
 
   bool HasLowYoungGenerationAllocationRate();