Always initialize the debugger eagerly.

src/isolate.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_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include "../include/v8-debug.h"
 #include "allocation.h"
 #include "assert-scope.h"
@@ skipping 910 matching lines @@
 
   RegExpStack* regexp_stack() { return regexp_stack_; }
 
   unibrow::Mapping<unibrow::Ecma262Canonicalize>*
       interp_canonicalize_mapping() {
     return &interp_canonicalize_mapping_;
   }
 
   inline bool IsCodePreAgingActive();
 
-  Debugger* debugger() {
-    if (!NoBarrier_Load(&debugger_initialized_)) InitializeDebugger();
-    return debugger_;
-  }
-  Debug* debug() {
-    if (!NoBarrier_Load(&debugger_initialized_)) InitializeDebugger();
-    return debug_;
-  }
+  Debugger* debugger() {  return debugger_; }
+  Debug* debug() { return debug_; }
 
   inline bool IsDebuggerActive();
   inline bool DebuggerHasBreakPoints();
 
   CpuProfiler* cpu_profiler() const { return cpu_profiler_; }
   HeapProfiler* heap_profiler() const { return heap_profiler_; }
 
 #ifdef DEBUG
   HistogramInfo* heap_histograms() { return heap_histograms_; }
 
@@ skipping 224 matching lines @@
 
   void MarkCompactPrologue(bool is_compacting,
                            ThreadLocalTop* archived_thread_data);
   void MarkCompactEpilogue(bool is_compacting,
                            ThreadLocalTop* archived_thread_data);
 
   void FillCache();
 
   void PropagatePendingExceptionToExternalTryCatch();
 
-  void InitializeDebugger();
-
   // Traverse prototype chain to find out whether the object is derived from
   // the Error object.
   bool IsErrorObject(Handle<Object> obj);
 
   Atomic32 id_;
   EntryStackItem* entry_stack_;
   int stack_trace_nesting_level_;
   StringStream* incomplete_message_;
   Address isolate_addresses_[kIsolateAddressCount + 1];  // NOLINT
   Bootstrapper* bootstrapper_;
@@ skipping 296 matching lines @@
   }
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ISOLATE_H_