Remove the debugger_ field from Isolate in a PRODUCT build

runtime/vm/isolate.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_ISOLATE_H_
 #define RUNTIME_VM_ISOLATE_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/atomic.h"
@@ skipping 301 matching lines @@
   Mutex* mutex() const { return mutex_; }
   Mutex* symbols_mutex() const { return symbols_mutex_; }
   Mutex* type_canonicalization_mutex() const {
     return type_canonicalization_mutex_;
   }
   Mutex* constant_canonicalization_mutex() const {
     return constant_canonicalization_mutex_;
   }
   Mutex* megamorphic_lookup_mutex() const { return megamorphic_lookup_mutex_; }
 
+#if !defined(PRODUCT)
   Debugger* debugger() const {
     if (!FLAG_support_debugger) {
       return NULL;
     }
     ASSERT(debugger_ != NULL);
     return debugger_;
   }
+#endif
 
   void set_single_step(bool value) { single_step_ = value; }
   bool single_step() const { return single_step_; }
   static intptr_t single_step_offset() {
     return OFFSET_OF(Isolate, single_step_);
   }
 
   // Lets the embedder know that a service message resulted in a resume request.
   void SetResumeRequest() {
     resume_request_ = true;
@@ skipping 420 matching lines @@
   int64_t start_time_micros_;
   Dart_Port main_port_;
   Dart_Port origin_id_;  // Isolates created by spawnFunc have some origin id.
   uint64_t pause_capability_;
   uint64_t terminate_capability_;
   bool errors_fatal_;
   void* init_callback_data_;
   Dart_EnvironmentCallback environment_callback_;
   Dart_LibraryTagHandler library_tag_handler_;
   ApiState* api_state_;
-  Debugger* debugger_;
+  NOT_IN_PRODUCT(Debugger* debugger_);
   bool resume_request_;
   int64_t last_resume_timestamp_;
   Random random_;
   Simulator* simulator_;
   Mutex* mutex_;          // Protects compiler stats.
   Mutex* symbols_mutex_;  // Protects concurrent access to the symbol table.
   Mutex* type_canonicalization_mutex_;      // Protects type canonicalization.
   Mutex* constant_canonicalization_mutex_;  // Protects const canonicalization.
   Mutex* megamorphic_lookup_mutex_;  // Protects megamorphic table lookup.
   MessageHandler* message_handler_;
@@ skipping 252 matching lines @@
   intptr_t* spawn_count_;
 
   Dart_IsolateFlags isolate_flags_;
   bool paused_;
   bool errors_are_fatal_;
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_ISOLATE_H_