Enable running of fasta tests on build bot.

pkg/testing/lib/src/chain.dart

 // Copyright (c) 2016, 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.md file.
 
 library testing.chain;
 
 import 'dart:async' show
     Future,
     Stream;
 
@@ skipping 161 matching lines @@
       /// interleaving steps.
       Future doStep(dynamic input) async {
         Future future;
         bool isAsync = false;
         if (iterator.moveNext()) {
           Step step = iterator.current;
           lastStepRun = step;
           isAsync = step.isAsync;
           logStepStart(completed, unexpectedResults.length, descriptions.length,
               suite, description, step);
+          // TODO(ahe): It's important to share the zone error reporting zone
+          // between all the tasks. Otherwise, if a future completes with an
+          // error in one zone, and gets stored, it becomes an uncaught error
+          // in other zones (this happened in createPlatform).
           future = runGuarded(() async {
             try {
               return await step.run(input, this);
             } catch (error, trace) {
               return step.unhandledError(error, trace);
             }
           }, printLineOnStdout: sb.writeln);
         } else {
           future = new Future.value(null);
         }
@@ skipping 19 matching lines @@
             } else if (result.outcome == Expectation.Fail) {
               result.addLog("Negative test reported an error as expeceted.\n");
             }
             result = toNegativeTestResult(result);
           }
           if (!expectedOutcomes.contains(result.outcome)) {
             result.addLog("$sb");
             unexpectedResults[description] = result;
             unexpectedOutcomes[description] = expectedOutcomes;
             logUnexpectedResult(suite, description, result, expectedOutcomes);
+            exitCode = 1;
           } else {
             logMessage(sb);
           }
           logTestComplete(++completed, unexpectedResults.length,
               descriptions.length, suite, description);
         });
         if (isAsync) {
           futures.add(future);
           return null;
         } else {
           return future;
         }
       }
       // The input of the first step is [description].
       await doStep(description);
     }
     await Future.wait(futures);
     logSuiteComplete();
     if (unexpectedResults.isNotEmpty) {
       unexpectedResults.forEach((TestDescription description, Result result) {
-        exitCode = 1;
         logUnexpectedResult(suite, description, result,
             unexpectedOutcomes[description]);
       });
       print("${unexpectedResults.length} failed:");
       unexpectedResults.forEach((TestDescription description, Result result) {
         print("${suite.name}/${description.shortName}: ${result.outcome}");
       });
     }
   }
 
@@ skipping 99 matching lines @@
 Future<Null> runChain(
     CreateContext f, Map<String, String> environment, Set<String> selectors,
     String json) {
   return withErrorHandling(() async {
     Chain suite = new Suite.fromJsonMap(Uri.base, JSON.decode(json));
     print("Running ${suite.name}");
     ChainContext context = await f(suite, environment);
     return context.run(suite, selectors);
   });
 }