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

pkg/polymer/lib/dwc.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.
-
-/** The entry point to the compiler. Used to implement `bin/dwc.dart`. */
-library dwc;
-
-import 'dart:async';
-import 'dart:io';
-import 'package:logging/logging.dart' show Level;
-
-import 'src/compiler.dart';
-import 'src/file_system/console.dart';
-import 'src/messages.dart';
-import 'src/compiler_options.dart';
-import 'src/utils.dart';
-
-void main() {
-  run(new Options().arguments).then((result) {
-    exit(result.success ? 0 : 1);
-  });
-}
-
-/** Contains the result of a compiler run. */
-class AnalysisResults {
-
-  /** False when errors were found by our polymer analyzer. */
-  final bool success;
-
-  /** Error and warning messages collected by the analyzer. */
-  final List<String> messages;
-
-  AnalysisResults(this.success, this.messages);
-}
-
-/**
- * Runs the polymer analyzer with the command-line options in [args].
- * See [CompilerOptions] for the definition of valid arguments.
- */
-// TODO(sigmund): rename to analyze? and rename file as analyzer.dart
-Future<AnalysisResults> run(List<String> args, {bool printTime,
-    bool shouldPrint: true}) {
-  var options = CompilerOptions.parse(args);
-  if (options == null) return new Future.value(new AnalysisResults(true, []));
-  if (printTime == null) printTime = options.verbose;
-
-  return asyncTime('Total time spent on ${options.inputFile}', () {
-    var messages = new Messages(options: options, shouldPrint: shouldPrint);
-    var compiler = new Compiler(new ConsoleFileSystem(), options, messages);
-    return compiler.run().then((_) {
-      var success = messages.messages.every((m) => m.level != Level.SEVERE);
-      var msgs = options.jsonFormat
-          ? messages.messages.map((m) => m.toJson())
-          : messages.messages.map((m) => m.toString());
-      return new AnalysisResults(success, msgs.toList());
-    });
-  }, printTime: printTime, useColors: options.useColors);
-}