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

runtime/bin/builtin_common.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 <stdio.h>
 
 #include "include/dart_api.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 #include "bin/platform.h"
 
 // Return the error from the containing function if handle is in error handle.
 #define RETURN_IF_ERROR(handle)                                                \
   {                                                                            \
     Dart_Handle __handle = handle;                                             \
     if (Dart_IsError((__handle))) {                                            \
       return __handle;                                                         \
     }                                                                          \
   }
 
 namespace dart {
 namespace bin {
 
 Dart_Handle Builtin::SetLoadPort(Dart_Port port) {
+  Dart_Handle builtin_lib =
+      Builtin::LoadAndCheckLibrary(Builtin::kBuiltinLibrary);
+  RETURN_IF_ERROR(builtin_lib);
+  // Set the _isolateId field.
+  Dart_Handle result = Dart_SetField(builtin_lib,
+                                     DartUtils::NewString("_isolateId"),
+                                     Dart_NewInteger(Dart_GetMainPortId()));
+  RETURN_IF_ERROR(result);
   load_port_ = port;
   ASSERT(load_port_ != ILLEGAL_PORT);
   Dart_Handle field_name = DartUtils::NewString("_loadPort");
   RETURN_IF_ERROR(field_name);
-  Dart_Handle builtin_lib =
-      Builtin::LoadAndCheckLibrary(Builtin::kBuiltinLibrary);
-  RETURN_IF_ERROR(builtin_lib);
   Dart_Handle send_port = Dart_GetField(builtin_lib, field_name);
   RETURN_IF_ERROR(send_port);
   if (!Dart_IsNull(send_port)) {
     // Already created and set.
     return Dart_True();
   }
   send_port = Dart_NewSendPort(load_port_);
   RETURN_IF_ERROR(send_port);
-  Dart_Handle result = Dart_SetField(builtin_lib, field_name, send_port);
+  result = Dart_SetField(builtin_lib, field_name, send_port);
   RETURN_IF_ERROR(result);
   return Dart_True();
 }
 
 }  // namespace bin
 }  // namespace dart