[heap] Remove js call rate heuristic from memory reducer.

src/heap/memory-reducer.h

Index: src/heap/memory-reducer.h
diff --git a/src/heap/memory-reducer.h b/src/heap/memory-reducer.h
index 4745001b6ccaca22a9b9701b1176cad522ba852c..0421987a3c5bc4d69016034ae2a88e632432878a 100644
--- a/src/heap/memory-reducer.h
+++ b/src/heap/memory-reducer.h
@@ -149,9 +149,6 @@ class V8_EXPORT_PRIVATE MemoryReducer {
 
   static bool WatchdogGC(const State& state, const Event& event);
 
-  // Returns the rate of JS calls initiated from the API.
-  double SampleAndGetJsCallsPerMs(double time_ms);
-
   Heap* heap_;
   State state_;
   unsigned int js_calls_counter_;