Fix Dart 1.17 strong-mode warnings.

test/result_test.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.
 
 import "dart:async";
 import "dart:collection";
 
 import "package:async/async.dart";
 import "package:stack_trace/stack_trace.dart";
 import "package:test/test.dart";
@@ skipping 39 matching lines @@
     Result<bool> result = new Result<bool>.error("BAD");
     expect(result.isValue, isFalse);
     expect(result.isError, isTrue);
     ErrorResult error = result.asError;
     expect(error.error, equals("BAD"));
     expect(error.stackTrace, isNull);
   });
 
   test("complete with value", () {
     Result<int> result = new ValueResult<int>(42);
-    Completer c = new Completer<int>();
+    var c = new Completer<int>();
     c.future.then(expectAsync((int v) { expect(v, equals(42)); }),
                   onError: (e, s) { fail("Unexpected error"); });
     result.complete(c);
   });
 
   test("complete with error", () {
     Result<bool> result = new ErrorResult("BAD", stack);
-    Completer c = new Completer<bool>();
+    var c = new Completer<bool>();
     c.future.then((bool v) { fail("Unexpected value $v"); },
                   onError: expectAsync((e, s) {
                     expect(e, equals("BAD"));
                     expect(s, same(stack));
                   }));
     result.complete(c);
   });
 
   test("add sink value", () {
-    Result<int> result = new ValueResult<int>(42);
+    var result = new ValueResult<int>(42);
     EventSink<int> sink = new TestSink(
         onData: expectAsync((v) { expect(v, equals(42)); })
     );
     result.addTo(sink);
   });
 
   test("add sink error", () {
     Result<bool> result = new ErrorResult("BAD", stack);
     EventSink<bool> sink = new TestSink(
         onError: expectAsync((e, s) {
@@ skipping 93 matching lines @@
                   cancelOnError: true);
     c.add(42);
     c.addError("BAD", stack);
     c.add(37);
     c.close();
   });
 
   test("release stream", () {
     StreamController<Result<int>> c = new StreamController<Result<int>>();
     Stream<int> stream = Result.releaseStream(c.stream);
-    List events = [new Result<int>.value(42),
+    var events = [new Result<int>.value(42),
                    new Result<int>.error("BAD", stack),
                    new Result<int>.value(37)];
     // Expect the data events, and an extra error event.
     var expectedList = new Queue.from(events)
         ..add(new Result.error("BAD2", stack));
 
     void dataListener(int v) {
       expect(expectedList.isEmpty, isFalse);
       Result expected = expectedList.removeFirst();
       expect(expected.isValue, isTrue);
@@ skipping 127 matching lines @@
   void add(T value) { onData(value); }
   void addError(error, [StackTrace stack]) { onError(error, stack); }
   void close() { onDone(); }
 
   static void _nullData(value) { fail("Unexpected sink add: $value"); }
   static void _nullError(e, StackTrace s) {
     fail("Unexpected sink addError: $e");
   }
   static void _nullDone() { fail("Unepxected sink close"); }
 }