pkg/observe: wrapMicrotask should return the result the provided testCase

pkg/observe/lib/transform.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.
 
 /**
  * Code transform for @observable. The core transformation is relatively
  * straightforward, and essentially like an editor refactoring.
  */
 library observe.transform;
 
 import 'dart:async';
 
 import 'package:analyzer_experimental/src/generated/ast.dart';
 import 'package:analyzer_experimental/src/generated/error.dart';
 import 'package:analyzer_experimental/src/generated/parser.dart';
 import 'package:analyzer_experimental/src/generated/scanner.dart';
 import 'package:barback/barback.dart';
-import 'package:path/path.dart' as path;
 import 'package:source_maps/refactor.dart';
 import 'package:source_maps/span.dart' show SourceFile;
 
 /**
  * A [Transformer] that replaces observables based on dirty-checking with an
  * implementation based on change notifications.
  *
  * The transformation adds hooks for field setters and notifies the observation
  * system of the change.
  */
@@ skipping 292 matching lines @@
 $type __\$$name$initializer;
 $type get $name => __\$$name;
 set $name($type value) {
   __\$$name = notifyPropertyChange(const Symbol('$name'), __\$$name, value);
 }
 '''.replaceAll('\n', '\n$indent'));
   }
 
   code.edit(begin, end, '$replace');
 }