Bring back initPolymer, allow boot.js only if using "polymer_experimental.html".

pkg/polymer/e2e_test/experimental_boot/test/import_test.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2014, 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 when using the deployed app.
-library canonicalization.dev3_test;
+library experimental_boot.test.import_test;
 
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_config.dart';
 import 'package:polymer/polymer.dart';
 
-import 'package:canonicalization3/a.dart';
-import 'packages/canonicalization3/b.dart';
-import 'package:canonicalization3/c.dart';
-import 'package:canonicalization3/d.dart' as d1;
-import 'packages/canonicalization3/d.dart' as d2;
+import 'package:experimental_boot/a.dart' show a;
+import 'packages/experimental_boot/b.dart' show b;
+import 'package:experimental_boot/c.dart' show c;
+import 'package:experimental_boot/d.dart' as d1 show d;
+import 'packages/experimental_boot/d.dart' as d2 show d;
 
 @initMethod
 main() {
   useHtmlConfiguration();
 
   setUp(() => Polymer.onReady);
 
-  test('canonicalization', () {
-    // "package:" urls work the same during development and deployment
+  test('canonicalization with experimental bootstrap', () {
     expect(a, 1, reason:
       'deploy picks the "package:" url as the canonical url for script tags.');
 
-    // relative urls do not. true, we shouldn't be using 'packages/' above, so
-    // that's ok.
+    // We shouldn't be using 'packages/' above, so that's ok.
     expect(b, 0, reason:
-      'deploy picks the "package:" url as the canonical url for script tags.');
+        'we pick the "package:" url as the canonical url for script tags.');
     expect(c, 2, reason: 'c was always imported with "package:" urls.');
     expect(d1.d, 2, reason: 'both a and b are loaded using package: urls');
-
-    // same here
     expect(d2.d, 0, reason: 'both a and b are loaded using package: urls');
   });
 }