Remove the debugger_ field from Isolate in a PRODUCT build

runtime/vm/exceptions.cc

 // Copyright (c) 2011, 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/exceptions.h"
 
 #include "platform/address_sanitizer.h"
 
 #include "lib/stacktrace.h"
 
@@ skipping 745 matching lines @@
 
   // Throw TypeError or CastError instance.
   Exceptions::ThrowByType(exception_type, args);
   UNREACHABLE();
 }
 
 void Exceptions::Throw(Thread* thread, const Instance& exception) {
   // Do not notify debugger on stack overflow and out of memory exceptions.
   // The VM would crash when the debugger calls back into the VM to
   // get values of variables.
+#if !defined(PRODUCT)
   if (FLAG_support_debugger) {
     Isolate* isolate = thread->isolate();
     if (exception.raw() != isolate->object_store()->out_of_memory() &&
         exception.raw() != isolate->object_store()->stack_overflow()) {
       isolate->debugger()->PauseException(exception);
     }
   }
+#endif
   // Null object is a valid exception object.
   ThrowExceptionHelper(thread, exception, StackTrace::Handle(thread->zone()),
                        false);
 }
 
 void Exceptions::ReThrow(Thread* thread,
                          const Instance& exception,
                          const Instance& stacktrace) {
   // Null object is a valid exception object.
   ThrowExceptionHelper(thread, exception, stacktrace, true);
@@ skipping 169 matching lines @@
       break;
   }
 
   Thread* thread = Thread::Current();
   NoReloadScope no_reload_scope(thread->isolate(), thread);
   return DartLibraryCalls::InstanceCreate(library, *class_name,
                                           *constructor_name, arguments);
 }
 
 }  // namespace dart