Replace bootstrap logic with 'boot.js', use 'component/dart' mime-type and add

pkg/polymer/example/canonicalization/test/dev3_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.
-
-/// Tests how canonicalization works during development.
-library canonicalization.dev3_test;
-
-import 'package:unittest/unittest.dart';
-import 'package:unittest/html_config.dart';
-import 'package:polymer/polymer.dart';
-
-import 'package:canonicalization/a.dart';
-import 'packages/canonicalization/b.dart';
-import 'package:canonicalization/c.dart';
-import 'package:canonicalization/d.dart' as d1;
-import 'packages/canonicalization/d.dart' as d2;
-
-main() {
-  initPolymer();
-  useHtmlConfiguration();
-
-  setUp(() => Polymer.onReady);
-
-  test('canonicalization', () {
-    expect(a, 1, reason:
-      'initPolymer picks the "package:" url as the canonical url for script '
-      'tags whose library is also loaded with a "package:" url.');
-    expect(b, 1, reason:
-      'initPolymer does nothing with script tags where the program doesn\'t '
-      'use a "package:" urls matching the same library.');
-    expect(c, 2, reason: 'c was always imported with "package:" urls.');
-    expect(d1.d, 1, reason: 'this matches the import from a');
-    expect(d2.d, 1, reason: 'this matches the import from b');
-  });
-}