Attempt to fix build bot by including Dart VM flags when invoking testee.

runtime/bin/vmservice/observatory/test/test_helper.dart

 // 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.
 
 library test_helper;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'package:unittest/unittest.dart';
 import 'package:observatory/service_io.dart';
 
 // This invocation should set up the state being tested.
 const String _TESTEE_MODE_FLAG = "--testee-mode";
 
 class _TestLauncher {
   Process process;
   final List<String> args;
 
   _TestLauncher() : args = ['--enable-vm-service:0',
                             Platform.script.toFilePath(),
                             _TESTEE_MODE_FLAG] {}
 
   Future<int> launch() {
     String dartExecutable = Platform.executable;
-    print('** Launching $args');
-    return Process.start(dartExecutable, args).then((p) {
+    var fullArgs = [];
+    fullArgs.addAll(Platform.executableArguments);
+    fullArgs.addAll(args);
+    print('** Launching $fullArgs');
+    return Process.start(dartExecutable, fullArgs).then((p) {
 
       Completer completer = new Completer();
       process = p;
       var portNumber;
       var blank;
       var first = true;
       process.stdout.transform(UTF8.decoder)
                     .transform(new LineSplitter()).listen((line) {
         if (line.startsWith('Observatory listening on http://')) {
           RegExp portExp = new RegExp(r"\d+.\d+.\d+.\d+:(\d+)");
@@ skipping 54 matching lines @@
     process.launch().then((port) {
       String addr = 'ws://localhost:$port/ws';
       new WebSocketVM(new WebSocketVMTarget(addr)).get('vm')
           .then((VM vm) => vm.isolates.first.load())
           .then((Isolate isolate) =>
               Future.forEach(tests, (test) => test(isolate)))
           .then((_) => exit(0));
     });
   }
 }