[observe] use consistent comment style

pkg/observe/test/transformer_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 'package:barback/barback.dart';
 import 'package:observe/transformer.dart';
 import 'package:unittest/compact_vm_config.dart';
 import 'package:unittest/unittest.dart';
 
@@ skipping 107 matching lines @@
     return _transform(code).then((output) {
       var begin = output.indexOf(constructor) + constructor.length - 1;
       var end = output.indexOf(';', begin);
       if (end == -1) end = output.length;
       var init = output.substring(begin, end).trim().replaceAll('  ', ' ');
       expect(init, expected);
     });
   });
 }
 
-/** Helper that applies the transform by creating mock assets. */
+/// Helper that applies the transform by creating mock assets.
 Future<String> _transform(String code) {
   var id = new AssetId('foo', 'a/b/c.dart');
   var asset = new Asset.fromString(id, code);
   var transformer = new ObservableTransformer();
   return transformer.isPrimary(asset).then((isPrimary) {
     expect(isPrimary, isTrue);
     var transform = new _MockTransform(asset);
     return transformer.apply(transform).then((_) {
       expect(transform.outs, hasLength(1));
       expect(transform.outs[0].id, id);
@@ skipping 68 matching lines @@
     "      Foo\n"
     "          get foo => __\$foo; Foo __\$foo/*D*/= 1; "
         "${_makeSetter('Foo', 'foo')} "
         "@reflectable @$meta @otherMetadata Foo get bar => __\$bar; "
         "Foo __\$bar =/*A*/2/*B*/; ${_makeSetter('Foo', 'bar')}\n"
     "          @reflectable @$meta @otherMetadata Foo get quux => __\$quux; "
         "Foo __\$quux/*C*/; ${_makeSetter('Foo', 'quux')}\n\n"
     "  @reflectable @$meta dynamic get baz => __\$baz; dynamic __\$baz; "
         "${_makeSetter('dynamic', 'baz')}\n"
     "}\n";