Add delegating initialize method for RuntimeCallTimerScope.

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/platform/elapsed-timer.h"
@@ skipping 1239 matching lines @@
                                RuntimeCallStats::CounterId counter_id);
 
   inline ~RuntimeCallTimerScope() {
     if (V8_UNLIKELY(isolate_ != nullptr)) {
       RuntimeCallStats::Leave(isolate_->counters()->runtime_call_stats(),
                               &timer_);
     }
   }
 
  private:
+  V8_INLINE void Initialize(Isolate* isolate,
+                            RuntimeCallStats::CounterId counter_id) {
+    isolate_ = isolate;
+    RuntimeCallStats::Enter(isolate_->counters()->runtime_call_stats(), &timer_,
+                            counter_id);
+  }
+
   Isolate* isolate_ = nullptr;
   RuntimeCallTimer timer_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COUNTERS_H_