Add support for attaching observatory to the server

pkg/analysis_server/test/timing/completion/completion_simple.dart

 // Copyright (c) 2014, 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.timing.simple;
 
 import 'dart:async';
+import 'dart:io';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:path/path.dart';
 
 import '../timing_framework.dart';
 
 /**
  * Perform the timing test, printing the minimum, average and maximum times, as
  * well as the standard deviation to the output.
  */
 void main(List<String> args) {
   SimpleTest test = new SimpleTest();
   test.run().then((TimingResult result) {
     print('minTime = ${result.minTime}');
     print('averageTime = ${result.averageTime}');
     print('maxTime = ${result.maxTime}');
     print('standardDeviation = ${result.standardDeviation}');
+    print('');
+    print('Press return to exit');
+    return stdin.first;
   });
 }
 
 /**
  * A test of how long it takes to get code completion results after making a
  * minor change inside a method body.
  */
 class SimpleTest extends TimingTest {
   /**
    * The path to the file in which code completion is to be performed.
@@ skipping 66 matching lines @@
     sendCompletionGetSuggestions(mainFilePath, cursorOffset + 1);
     return completionReceived.future;
   }
 
   @override
   Future tearDown() {
     sendAnalysisSetAnalysisRoots([], []);
     return new Future.value();
   }
 }