Switch polymer's build.dart to use the new linter. This CL does the following

pkg/polymer/lib/src/file_system/console.dart

-// Copyright (c) 2012, 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 console;
-
-import 'dart:async';
-import 'dart:convert';
-import 'dart:io';
-import 'package:polymer/src/file_system.dart';
-
-/** File system implementation for console VM (i.e. no browser). */
-class ConsoleFileSystem implements FileSystem {
-
-  /** Pending futures for file write requests. */
-  final _pending = <String, Future>{};
-
-  Future flush() => Future.wait(_pending.values.toList());
-
-  void writeString(String path, String text) {
-    if(!_pending.containsKey(path)) {
-      _pending[path] = new File(path).open(mode: FileMode.WRITE)
-          .then((file) => file.writeString(text))
-          .then((file) => file.close())
-          .whenComplete(() { _pending.remove(path); });
-    }
-  }
-
-  // TODO(jmesserly): even better would be to pass the RandomAccessFile directly
-  // to html5lib. This will require a further restructuring of FileSystem.
-  // Probably it just needs "readHtml" and "readText" methods.
-  Future<List<int>> readTextOrBytes(String path) {
-    return new File(path).open().then(
-        (file) => file.length().then((length) {
-      // TODO(jmesserly): is this guaranteed to read all of the bytes?
-      var buffer = new List<int>(length);
-      return file.readInto(buffer, 0, length)
-          .then((_) => file.close())
-          .then((_) => buffer);
-    }));
-  }
-
-  // TODO(jmesserly): do we support any encoding other than UTF-8 for Dart?
-  Future<String> readText(String path) {
-    return readTextOrBytes(path).then(UTF8.decode);
-  }
-}