[polymer] switch comment style

pkg/polymer/test/build/common.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.
 
 library polymer.test.build.common;
 
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 import 'package:stack_trace/stack_trace.dart';
 import 'package:unittest/unittest.dart';
 
 String idToString(AssetId id) => '${id.package}|${id.path}';
 AssetId idFromString(String s) {
   int index = s.indexOf('|');
   return new AssetId(s.substring(0, index), s.substring(index + 1));
 }
 
 String _removeTrailingWhitespace(String str) =>
     str.splitMapJoin('\n',
         onNonMatch: (s) => s.replaceAll(new RegExp(r'\s+$'), ''));
 
-/**
- * A helper package provider that has files stored in memory, also wraps
- * [Barback] to simply our tests.
- */
+/// A helper package provider that has files stored in memory, also wraps
+/// [Barback] to simply our tests.
 class TestHelper implements PackageProvider {
-  /**
-   * Maps from an asset string identifier of the form 'package|path' to the
-   * file contents.
-   */
+  /// Maps from an asset string identifier of the form 'package|path' to the
+  /// file contents.
   final Map<String, String> files;
   final Iterable<String> packages;
   final List<String> messages;
   int messagesSeen = 0;
   bool errorSeen = false;
 
   Barback barback;
   var errorSubscription;
   var resultSubscription;
   var logSubscription;
@@ skipping 39 matching lines @@
       expect('$msg$spanInfo', messages[messagesSeen++]);
     });
   }
 
   void tearDown() {
     errorSubscription.cancel();
     resultSubscription.cancel();
     logSubscription.cancel();
   }
 
-  /**
-   * Tells barback which files have changed, and thus anything that depends on
-   * it on should be computed. By default mark all the input files.
-   */
+  /// Tells barback which files have changed, and thus anything that depends on
+  /// it on should be computed. By default mark all the input files.
   void run([Iterable<String> paths]) {
     if (paths == null) paths = files.keys;
     barback.updateSources(paths.map(idFromString));
   }
 
   Future<String> operator [](String assetString){
     return barback.getAssetById(idFromString(assetString))
         .then((asset) => asset.readAsString());
   }
 
@@ skipping 31 matching lines @@
   });
 }
 
 const WEB_COMPONENTS_TAG =
     '<script src="packages/web_components/platform.js"></script>\n'
     '<script src="packages/web_components/dart_support.js"></script>\n';
 
 const INTEROP_TAG = '<script src="packages/browser/interop.js"></script>\n';
 const DART_JS_TAG = '<script src="packages/browser/dart.js"></script>';