Rework standalone to use a synchronous loader that does not invoke Dart code

runtime/lib/vmservice.cc

 // Copyright (c) 2015, 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/bootstrap_natives.h"
 #include "vm/dart_api_impl.h"
 #include "vm/datastream.h"
 #include "vm/exceptions.h"
 #include "vm/flags.h"
 #include "vm/growable_array.h"
 #include "vm/message.h"
+#include "vm/message_handler.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/port.h"
 #include "vm/service_isolate.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
 DECLARE_FLAG(bool, trace_service);
 
@@ skipping 110 matching lines @@
   }
   Isolate::VisitIsolates(&register_isolates);
 #endif
   return Object::null();
 }
 
 
 DEFINE_NATIVE_ENTRY(VMService_OnExit, 0) {
   if (FLAG_trace_service) {
     OS::Print("vm-service: processed exit message.\n");
+    MessageHandler* message_handler = isolate->message_handler();
+    OS::Print("vm-service: live ports = %" Pd "\n",
+              message_handler->live_ports());
   }
   return Object::null();
 }
 
 
 DEFINE_NATIVE_ENTRY(VMService_OnServerAddressChange, 1) {
   if (!FLAG_support_service) {
     return Object::null();
   }
   GET_NATIVE_ARGUMENT(String, address, arguments->NativeArgAt(0));
@@ skipping 279 matching lines @@
     idx += 2;
   }
 
   return result_list.raw();
 #else
   return Object::null();
 #endif
 }
 
 }  // namespace dart