Improvements to causal async stack traces

runtime/observatory/tests/service/test_helper.dart

 // Copyright (c) 2013, 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_helper;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'package:observatory/service_io.dart';
-import 'package:stack_trace/stack_trace.dart';
 import 'service_test_common.dart';
 
 /// Will be set to the http address of the VM's service protocol before
 /// any tests are invoked.
 String serviceHttpAddress;
 String serviceWebsocketAddress;
 
 const String _TESTEE_ENV_KEY = 'SERVICE_TEST_TESTEE';
 const Map<String, String> _TESTEE_SPAWN_ENV = const {
   _TESTEE_ENV_KEY: 'true'
@@ skipping 265 matching lines @@
                    testeeControlsServer,
                    useAuthToken, extraArgs).then((Uri serverAddress) async {
       if (mainArgs.contains("--gdb")) {
         var pid = process.process.pid;
         var wait = new Duration(seconds: 10);
         print("Testee has pid $pid, waiting $wait before continuing");
         sleep(wait);
       }
       setupAddresses(serverAddress);
       var name = Platform.script.pathSegments.last;
-      Chain.capture(() async {
+      try {
         var vm =
             new WebSocketVM(new WebSocketVMTarget(serviceWebsocketAddress));
         print('Loading VM...');
         await vm.load();
         print('Done loading VM');
 
         // Run vm tests.
         if (vmTests != null) {
           var testIndex = 1;
           var totalTests = vmTests.length;
@@ skipping 14 matching lines @@
             vm.verbose = verbose_vm;
             print('Running $name [$testIndex/$totalTests]');
             testIndex++;
             await test(isolate);
           }
         }
 
         print('All service tests completed successfully.');
         testsDone = true;
         await process.requestExit();
-      }, onError: (error, stackTrace) {
+      } catch (error, stackTrace) {
         if (testsDone) {
           print('Ignoring late exception during process exit:\n'
                 '$error\n#stackTrace');
         } else {
           process.requestExit();
           print('Unexpected exception in service tests: $error\n$stackTrace');
-          throw error;
+          rethrow;
         }
-      });
+      }
     });
   }
 
 
 
   Future<Isolate> getFirstIsolate(WebSocketVM vm) async {
     if (vm.isolates.isNotEmpty) {
       var isolate = await vm.isolates.first.load();
       if (isolate is Isolate) {
         return isolate;
@@ skipping 129 matching lines @@
     new _ServiceTesterRunner().run(
         mainArgs: mainArgs,
         extraArgs: extraArgs,
         vmTests: tests,
         pause_on_start: pause_on_start,
         pause_on_exit: pause_on_exit,
         verbose_vm: verbose_vm,
         pause_on_unhandled_exceptions: pause_on_unhandled_exceptions);
   }
 }