Initialize the Isolate's use_counter_callback_ member

src/isolate.cc

 // 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.
 
 #include <stdlib.h>
 
 #include "src/v8.h"
 
 #include "src/ast.h"
 #include "src/bootstrapper.h"
@@ skipping 1462 matching lines @@
       has_fatal_error_(false),
       initialized_from_snapshot_(false),
       cpu_profiler_(NULL),
       heap_profiler_(NULL),
       function_entry_hook_(NULL),
       deferred_handles_head_(NULL),
       optimizing_compiler_thread_(NULL),
       sweeper_thread_(NULL),
       num_sweeper_threads_(0),
       stress_deopt_count_(0),
-      next_optimization_id_(0) {
+      next_optimization_id_(0),
+      use_counter_callback_(NULL) {
   id_ = base::NoBarrier_AtomicIncrement(&isolate_counter_, 1);
   TRACE_ISOLATE(constructor);
 
   memset(isolate_addresses_, 0,
       sizeof(isolate_addresses_[0]) * (kIsolateAddressCount + 1));
 
   heap_.isolate_ = this;
   stack_guard_.isolate_ = this;
 
   // ThreadManager is initialized early to support locking an isolate
@@ skipping 868 matching lines @@
   // The simulator uses a separate JS stack.
   Address jssp_address = Simulator::current(isolate_)->get_sp();
   uintptr_t jssp = reinterpret_cast<uintptr_t>(jssp_address);
   if (jssp < stack_guard->real_jslimit()) return true;
 #endif  // USE_SIMULATOR
   return reinterpret_cast<uintptr_t>(this) < stack_guard->real_climit();
 }
 
 
 } }  // namespace v8::internal