Remove the debugger_ field from Isolate in a PRODUCT build

runtime/vm/flow_graph_compiler.cc

 // 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.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 67 matching lines @@
     FLAG_reorder_basic_blocks = false;
     FLAG_use_field_guards = false;
     FLAG_use_cha_deopt = false;
     FLAG_unbox_numeric_fields = false;
     FLAG_enable_mirrors = false;
 
 #if !defined(PRODUCT) && !defined(DART_PRECOMPILED_RUNTIME)
     // Set flags affecting runtime accordingly for dart_bootstrap.
     // These flags are constants with PRODUCT and DART_PRECOMPILED_RUNTIME.
     FLAG_collect_code = false;
-    FLAG_support_debugger = false;
     FLAG_deoptimize_alot = false;  // Used in some tests.
     FLAG_deoptimize_every = 0;     // Used in some tests.
     FLAG_load_deferred_eagerly = true;
     FLAG_print_stop_message = false;
     FLAG_use_osr = false;
 #endif
   }
 }
 
 DEFINE_FLAG_HANDLER(PrecompilationModeHandler,
@@ skipping 1841 matching lines @@
   return true;
 }
 
 void FlowGraphCompiler::FrameStateClear() {
   ASSERT(!is_optimizing());
   frame_state_.TruncateTo(0);
 }
 #endif  // defined(DEBUG) && !defined(TARGET_ARCH_DBC)
 
 }  // namespace dart