Ensure counters are initialized, to avoid init on non-joinable threads.

src/counters.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COUNTERS_H_
 #define V8_COUNTERS_H_
 
 #include "include/v8.h"
 #include "src/allocation.h"
 #include "src/base/atomic-utils.h"
@@ skipping 1255 matching lines @@
 #undef COUNTER_ID
 #define COUNTER_ID(name) kCountOfCODE_AGE__##name, \
     kSizeOfCODE_AGE__##name,
     CODE_AGE_LIST_COMPLETE(COUNTER_ID)
 #undef COUNTER_ID
     stats_counter_count
   };
 
   void ResetCounters();
   void ResetHistograms();
+  void InitializeHistograms();
+
   RuntimeCallStats* runtime_call_stats() { return &runtime_call_stats_; }
 
  private:
 #define HR(name, caption, min, max, num_buckets) Histogram name##_;
   HISTOGRAM_RANGE_LIST(HR)
 #undef HR
 
 #define HT(name, caption, max, res) HistogramTimer name##_;
   HISTOGRAM_TIMER_LIST(HT)
 #undef HT
@@ skipping 55 matching lines @@
 
   explicit Counters(Isolate* isolate);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(Counters);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COUNTERS_H_