Avoid analysis server crash when reanalyze invoked during analysis.

pkg/analysis_server/test/integration/integration_tests.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.integration.analysis;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
@@ skipping 136 matching lines @@
     sourceDirectory = Directory.systemTemp.createTempSync('analysisServer');
 
     onAnalysisErrors.listen((AnalysisErrorsParams params) {
       currentAnalysisErrors[params.file] = params.errors;
     });
     Completer serverConnected = new Completer();
     onServerConnected.listen((_) {
       expect(serverConnected.isCompleted, isFalse);
       serverConnected.complete();
     });
+    onServerError.listen((ServerErrorParams params) {
+      // A server error should never happen during an integration test.
+      fail(params.message);
+    });
     return server.start().then((_) {
       server.listenToOutput(dispatchNotification);
       server.exitCode.then((_) {
         skipShutdown = true;
       });
       return serverConnected.future;
     });
   }
 
   /**
@@ skipping 701 matching lines @@
    */
   void _recordStdio(String line) {
     double elapsedTime = _time.elapsedTicks / _time.frequency;
     line = "$elapsedTime: $line";
     if (_debuggingStdio) {
       print(line);
     }
     _recordedStdio.add(line);
   }
 }