Use hash map for event handler file descriptor map

tests/standalone/src/ProcessStderrTest.dart

 // Copyright (c) 2011, 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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 #library("ProcessStderrTest");
 #source("ProcessTestUtil.dart");
 
-void test(Process process) {
+void test(Process process, int expectedExitCode) {
   // Wait for the process to start and then interact with it.
   process.startHandler = () {
     List<int> data = "ABCDEFGHI\n".charCodes();
     final int dataSize = data.length;
 
     InputStream input = process.stderr;
     OutputStream output = process.stdin;
 
     int received = 0;
     List<int> buffer = [];
@@ skipping 16 matching lines @@
         } else if (received === dataSize) {
           process.close();
         }
       }
     }
 
     output.write(data);
     output.close();
     input.dataHandler = readData;
   };
+
+  process.exitHandler = (exitCode) {
+    Expect.equals(expectedExitCode, exitCode);
+  };
 }
 
 main() {
   // Run the test using the process_test binary.
   test(new Process.start(getProcessTestFileName(),
-                         const ["1", "1", "99", "0"]));
+                         const ["1", "1", "99", "0"]), 99);
 
   // Run the test using the dart binary with an echo script.
   // The test runner can be run from either the root or from runtime.
   var scriptFile = new File("tests/standalone/src/ProcessStdIOScript.dart");
   if (!scriptFile.existsSync()) {
     scriptFile = new File("../tests/standalone/src/ProcessStdIOScript.dart");
   }
   Expect.isTrue(scriptFile.existsSync());
-  test(new Process.start(getDartFileName(), [scriptFile.name, "1"]));
+  test(new Process.start(getDartFileName(), [scriptFile.name, "1"]), 0);
 }