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

pkg/polymer/lib/testing/content_shell_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.
-
-/**
- * Helper library to run tests in content_shell
- */
-library polymer.testing.end2end;
-
-import 'dart:io';
-import 'package:args/args.dart';
-import 'package:path/path.dart' as path;
-import 'package:unittest/unittest.dart';
-import 'package:polymer/deploy.dart' as deploy;
-
-
-/**
- * Compiles [testFile] with the web-ui compiler, and then runs the output as a
- * unit test in content_shell.
- */
-void endToEndTests(String inputDir, String outDir, {List<String> arguments}) {
-  _testHelper(new _TestOptions(inputDir, inputDir, null, outDir,
-      arguments: arguments));
-}
-
-/**
- * Compiles [testFile] with the web-ui compiler, and then runs the output as a
- * render test in content_shell.
- */
-void renderTests(String webDir, String inputDir, String expectedDir,
-    String outDir, {List<String> arguments, String script, String pattern,
-    bool deleteDir: true}) {
-  _testHelper(new _TestOptions(webDir, inputDir, expectedDir, outDir,
-      arguments: arguments, script: script, pattern: pattern,
-      deleteDir: deleteDir));
-}
-
-void _testHelper(_TestOptions options) {
-  expect(options, isNotNull);
-
-  var paths = new Directory(options.inputDir).listSync()
-      .where((f) => f is File).map((f) => f.path)
-      .where((p) => p.endsWith('_test.html') && options.pattern.hasMatch(p));
-
-  if (paths.isEmpty) return;
-
-  // First clear the output folder. Otherwise we can miss bugs when we fail to
-  // generate a file.
-  var dir = new Directory(options.outDir);
-  if (dir.existsSync() && options.deleteDir) {
-    print('Cleaning old output for ${path.normalize(options.outDir)}');
-    dir.deleteSync(recursive: true);
-  }
-  dir.createSync(recursive: true);
-
-  for (var filePath in paths) {
-    var filename = path.basename(filePath);
-    test('compile $filename', () {
-      return deploy.runForTest(options.webDir, options.outDir);
-    });
-  }
-
-  var filenames = paths.map(path.basename).toList();
-  // Sort files to match the order in which run.sh runs diff.
-  filenames.sort();
-
-  var finalOutDir = path.join(options.outDir, options.inputDir);
-  var outBaseDir = path.join(options.outDir, options.webDir);
-
-  runTests(String search) {
-    var output;
-
-    for (var filename in filenames) {
-      test('content_shell run $filename$search', () {
-        var lnArgs = ['-s', '$outBaseDir/packages', '$finalOutDir/packages'];
-        return Process.run('ln', lnArgs).then((_) {
-          var args = ['--dump-render-tree',
-              'file://$finalOutDir/$filename$search'];
-          var env = {'DART_FLAGS': '--checked'};
-          return Process.run('content_shell', args, environment: env)
-              .then((res) {
-                expect(res.exitCode, 0, reason: 'content_shell exit code: '
-                    '${res.exitCode}. Contents of stderr: \n${res.stderr}');
-                var outs = res.stdout.split('#EOF\n')
-                  .where((s) => !s.trim().isEmpty).toList();
-                expect(outs.length, 1);
-                output = outs.first;
-              });
-        });
-      });
-
-      test('verify $filename $search', () {
-        expect(output, isNotNull, reason:
-          'Output not available, maybe content_shell failed to run.');
-        var outPath = path.join(options.outDir, '$filename.txt');
-        new File(outPath).writeAsStringSync(output);
-        if (options.isRenderTest) {
-          var expectedPath = path.join(options.expectedDir, '$filename.txt');
-          var expected = new File(expectedPath).readAsStringSync();
-          expect(output, expected, reason: 'unexpected output for <$filename>');
-        } else {
-          bool passes = matches(
-              new RegExp('All .* tests passed')).matches(output, {});
-          expect(passes, true, reason: 'unit test failed:\n$output');
-        }
-      });
-    }
-  }
-
-  bool compiled = false;
-  ensureCompileToJs() {
-    if (compiled) return;
-    compiled = true;
-
-    for (var filename in filenames) {
-      test('dart2js $filename', () {
-        // TODO(jmesserly): this depends on DWC's output scheme.
-        // Alternatively we could use html5lib to find the script tag.
-        var inPath = '${filename}_bootstrap.dart';
-        var outPath = '${inPath}.js';
-
-        inPath = path.join(finalOutDir, inPath);
-        outPath = path.join(finalOutDir, outPath);
-
-        expect(Process.run('dart2js', ['-o$outPath', inPath]).then((res) {
-          expect(res.exitCode, 0, reason: 'dart2js exit code: '
-            '${res.exitCode}. Contents of stderr: \n${res.stderr}. '
-            'Contents of stdout: \n${res.stdout}.');
-          expect(new File(outPath).existsSync(), true, reason: 'input file '
-            '$inPath should have been compiled to $outPath.');
-        }), completes);
-      });
-    }
-  }
-
-  if (options.runAsDart) {
-    runTests('');
-  }
-  if (options.runAsJs) {
-    ensureCompileToJs();
-    runTests('?js=1');
-  }
-  if (options.forcePolyfillShadowDom) {
-    ensureCompileToJs();
-    runTests('?js=1&shadowdomjs=1');
-  }
-}
-
-class _TestOptions {
-  final String webDir;
-  final String inputDir;
-
-  final String expectedDir;
-  bool get isRenderTest => expectedDir != null;
-
-  final String outDir;
-  final bool deleteDir;
-
-  final bool runAsDart;
-  final bool runAsJs;
-  final bool forcePolyfillShadowDom;
-
-  final List<String> compilerArgs;
-  final RegExp pattern;
-
-  factory _TestOptions(String webDir, String inputDir, String expectedDir,
-      String outDir, {List<String> arguments, String script, String pattern,
-      bool deleteDir: true}) {
-    if (arguments == null) arguments = new Options().arguments;
-    if (script == null) script = new Options().script;
-
-    var args = _parseArgs(arguments, script);
-    if (args == null) return null;
-    var compilerArgs = args.rest;
-    var filePattern;
-    if (pattern != null) {
-      filePattern = new RegExp(pattern);
-    } else if (compilerArgs.length > 0) {
-      filePattern = new RegExp(compilerArgs[0]);
-      compilerArgs = compilerArgs.sublist(1);
-    } else {
-      filePattern = new RegExp('.');
-    }
-
-    var scriptDir = path.absolute(path.dirname(script));
-    webDir = path.relative(path.join(scriptDir, webDir));
-    inputDir = path.relative(path.join(scriptDir, inputDir));
-    outDir = path.join(scriptDir, outDir);
-    if (expectedDir != null) {
-      expectedDir = path.join(scriptDir, expectedDir);
-    }
-
-    return new _TestOptions._(webDir, inputDir, expectedDir, outDir, deleteDir,
-        args['dart'] == true, args['js'] == true, args['shadowdom'] == true,
-        compilerArgs, filePattern);
-  }
-
-  _TestOptions._(this.webDir, this.inputDir, this.expectedDir, this.outDir,
-      this.deleteDir, this.runAsDart, this.runAsJs,
-      this.forcePolyfillShadowDom, this.compilerArgs, this.pattern);
-}
-
-ArgResults _parseArgs(List<String> arguments, String script) {
-  var parser = new ArgParser()
-    ..addFlag('dart', abbr: 'd', help: 'run on Dart VM', defaultsTo: true)
-    ..addFlag('js', abbr: 'j', help: 'run compiled dart2js', defaultsTo: true)
-    ..addFlag('shadowdom', abbr: 's',
-        help: 'run dart2js and polyfilled ShadowDOM', defaultsTo: true)
-    ..addFlag('help', abbr: 'h', help: 'Displays this help message',
-        defaultsTo: false, negatable: false);
-
-  showUsage() {
-    print('Usage: $script [options...] [test_name_regexp]');
-    print(parser.getUsage());
-    return null;
-  }
-
-  try {
-    var results = parser.parse(arguments);
-    if (results['help']) return showUsage();
-    return results;
-  } on FormatException catch (e) {
-    print(e.message);
-    return showUsage();
-  }
-}