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

pkg/polymer/e2e_test/canonicalization/test/dir/dev_common.dart

+// 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 developing in Dartium. This is
+/// identical to the code in ../dir/deploy_common.dart but we need to copy it
+/// here because the 'packages/...' URLs below should be relative from the
+/// entrypoint directory.
+library canonicalization.test.dir.dev_common;
+
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+import 'package:polymer/polymer.dart';
+
+import 'package:canonicalization/a.dart' show a;
+import 'packages/canonicalization/b.dart' show b;
+import 'package:canonicalization/c.dart' show c;
+import 'package:canonicalization/d.dart' as d1 show d;
+import 'packages/canonicalization/d.dart' as d2 show d;
+
+main() {
+  initPolymer();
+  useHtmlConfiguration();
+
+  setUp(() => Polymer.onReady);
+
+  test('canonicalization', () {
+    expect(a, 1, reason: 'Dartium loads "a" via a "package:" url.');
+
+    // We shouldn't be using 'packages/', but we do just to check that Dartium
+    // can't infer a "package:" url for it.
+    expect(b, 1, reason: 'Dartium picks the relative url for "b".');
+    expect(c, 2, reason: '"c" was always imported with "package:" urls.');
+    expect(d1.d, 1, reason: '"a" loads via "package:", but "b" does not.');
+    expect(d2.d, 1, reason: '"b" loads via a relative url, but "a" does not.');
+  });
+}