Fix test 'platform_executable_test'

tests/standalone/io/platform_executable_test.dart

 // 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.
 //
 // Process test program to test process communication.
 
 library PlatformExecutableTest;
 
 import "dart:io";
 
@@ skipping 28 matching lines @@
 }
 
 void testDartExecShouldNotBeInCurrentDir() {
   var type = FileSystemEntity.typeSync(platformExeName);
   expectEquals(FileSystemEntityType.NOT_FOUND, type);
 }
 
 void testShouldFailOutsidePath() {
   var threw = false;
   try {
-    Process.runSync(platformExeName, [platformExeName], 
-      includeParentEnvironment: false, environment: {_SCRIPT_KEY: 'yes'});
+    Process.runSync(platformExeName, ['--version'],
+                    includeParentEnvironment: false,
+                    environment: {_SCRIPT_KEY: 'yes', 'PATH': ''});
   } catch (_) {
     threw = true;
   }
 
   if (!threw) {
     throw 'Expected running the dart executable – "$platformExeName" without'
           ' the parent environment or path to fail.';
   }
 }
 
@@ skipping 82 matching lines @@
 
   testDartExecShouldNotBeInCurrentDir();
   testShouldSucceedWithSourcePlatformExecutable(); /// 00: ok
   withTempDir(testExeSymLinked); /// 01: ok
   withTempDir(testExeDirSymLinked); /// 02: ok
   testPathToSDKDir(); /// 03: ok
   withTempDir(testPathPointsToSymLinkedSDKPath); /// 04: ok
   withTempDir(testPathToDirWithExeSymLinked); /// 05: ok
   testShouldFailOutsidePath(); /// 06: ok
 }