Fix the remaining strong mode warnings.

test/chain/chain_test.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:async';
 
 import 'package:path/path.dart' as p;
 import 'package:stack_trace/stack_trace.dart';
 import 'package:test/test.dart';
 
 import 'utils.dart';
 
+typedef void ChainErrorCallback(stack, Chain chain);
+
 void main() {
   group('Chain.parse()', () {
     test('parses a real Chain', () {
       return captureFuture(() => inMicrotask(() => throw 'error'))
           .then((chain) {
         expect(new Chain.parse(chain.toString()).toString(),
             equals(chain.toString()));
       });
     });
 
@@ skipping 18 matching lines @@
       expect(Chain.capture(() => new Future.error("oh no"), when: false),
           throwsA("oh no"));
     });
 
     test("with onError blocks errors", () {
       Chain.capture(() {
         return new Future.error("oh no");
       }, onError: expectAsync((error, chain) {
         expect(error, equals("oh no"));
         expect(chain, new isInstanceOf<Chain>());
-      }), when: false);
+      }) as ChainErrorCallback, when: false);
+      // TODO(rnystrom): Remove this cast if expectAsync() gets a better type.

[nweiz, 2016/04/08 00:24:03]

I generally haven't been making tests strong mode clean yet, since test itself
isn't strong mode clean and there's not a great way to ensure that they stay
clean.

     });
   });
 
   test("toString() ensures that all traces are aligned", () {
     var chain = new Chain([
       new Trace.parse('short 10:11  Foo.bar\n'),
       new Trace.parse('loooooooooooong 10:11  Zop.zoop')
     ]);
 
     expect(chain.toString(), equals(
@@ skipping 241 matching lines @@
         controller = new StreamController()..addError('error', trace);
         expect(Chain.track(controller.stream).toList()
             .catchError((e, stackTrace) {
           expect(e, equals('error'));
           expect(stackTrace.toString(), equals(trace.toString()));
         }), completes);
       });
     });
   });
 }