Beef up analysis server integration test messages.

pkg/analysis_server/test/timing/timing_framework.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;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 
@@ skipping 294 matching lines @@
    * Shut the server down unless [skipShutdown] is `true`.
    */
   Future _shutdownIfNeeded() {
     if (skipShutdown) {
       return new Future.value();
     }
     // Give the server a short time to comply with the shutdown request; if it
     // doesn't exit, then forcibly terminate it.
     sendServerShutdown();
     return server.exitCode.timeout(SHUTDOWN_TIMEOUT, onTimeout: () {
-      return server.kill();
+      return server.kill('server failed to exit');
     });
   }
 }