Don't exit test script on an error in the http server.

tools/testing/dart/http_server.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.
 
 library http_server;
 
 import 'dart:io';
 import 'dart:isolate';
 import 'test_suite.dart';  // For TestUtils.
 import '../../../pkg/args/lib/args.dart';
@@ skipping 55 matching lines @@
   static setPackageRootDir(Map configuration) {
     _packageRootDir = TestUtils.currentWorkingDirectory.join(
         new Path(TestUtils.buildDir(configuration)));
   }
 
   static startHttpServer(String host, {int allowedPort:-1, int port: 0}) {
     var basePath = TestUtils.dartDir();
     var httpServer = new HttpServer();
     var packagesDirName = 'packages';
     httpServer.onError = (e) {
-      // Consider errors in the builtin http server fatal.
-      // Intead of just throwing the exception we print
-      // a message that makes it clearer what happened.
+      // TODO(ricow): Once we have a debug log we should write this out there.
       print('Test http server error: $e');
-      exit(1);
     };
     httpServer.defaultRequestHandler = (request, resp) {
       var requestPath = new Path(request.path.substring(1)).canonicalize();
       var path = basePath.join(requestPath);
       var file = new File(path.toNativePath());
 
       if (requestPath.segments().contains(packagesDirName)) {
         // Essentially implement the packages path rewriting, so we don't have
         // to pass environment variables to the browsers.
         var requestPathStr = requestPath.toNativePath().substring(
@@ skipping 45 matching lines @@
     });
 
     httpServer.listen(host, port);
     serverList.add(httpServer);
   }
 
   static terminateHttpServers() {
     for (var server in serverList) server.close();
   }
 }