Add new Dart API call Dart_MakeIsolateRunnable(). This would allow an

runtime/bin/main.cc

 // Copyright (c) 2012, 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 <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "include/dart_api.h"
 #include "include/dart_debugger_api.h"
@@ skipping 460 matching lines @@
   if (!Dart_IsLibrary(library)) {
     char errbuf[256];
     snprintf(errbuf, sizeof(errbuf),
              "Expected a library when loading script: %s",
              script_uri);
     *error = strdup(errbuf);
     Dart_ExitScope();
     Dart_ShutdownIsolate();
     return false;
   }
+
+  // Make the isolate runnable so that it is ready to handle messages.
+  result = Dart_MakeIsolateRunnable();
+  CHECK_RESULT(result);
+
   Dart_ExitScope();
   VmStats::AddIsolate(reinterpret_cast<IsolateData*>(data), isolate);
   return true;
 }
 
 
 static bool CreateIsolateAndSetup(const char* script_uri,
                                   const char* main,
                                   void* data, char** error) {
   return CreateIsolateAndSetupHelper(script_uri,
@@ skipping 340 matching lines @@
   Dart_ShutdownIsolate();
   // Terminate process exit-code handler.
   Process::TerminateExitCodeHandler();
   // Free copied argument strings if converted.
   if (argv_converted) {
     for (int i = 0; i < argc; i++) free(argv[i]);
   }
 
   return Process::GlobalExitCode();
 }