upgrade dependencies, including migration to package:test

test/runtime/dart_runtime_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.
 
 // Test code
 import 'dart:collection';
 import 'dart:mirrors';
-import 'package:unittest/unittest.dart';
+import 'package:test/test.dart';
 import 'package:dev_compiler/config.dart';
 import 'package:dev_compiler/runtime/dart_runtime.dart';
 
 final bool intIsNonNullable = TypeOptions.NONNULLABLE_TYPES.contains('int');
 final bool doubleIsNonNullable =
     TypeOptions.NONNULLABLE_TYPES.contains('double');
 
 class A {
   int x;
 }
@@ skipping 307 matching lines @@
 
     var objectChecker = new Checker<Object>();
     objectChecker.isGround(true);
     objectChecker.isGroundList(true);
 
     objectChecker.check(5, true);
     objectChecker.check("hello", true);
     objectChecker.check(null, true);
   });
 }