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

pkg/polymer/e2e_test/bad_import3/lib/b.html

Index: pkg/polymer/e2e_test/bad_import3/lib/b.html
diff --git a/pkg/polymer/example/canonicalization3/lib/b.html b/pkg/polymer/e2e_test/bad_import3/lib/b.html
similarity index 52%
rename from pkg/polymer/example/canonicalization3/lib/b.html
rename to pkg/polymer/e2e_test/bad_import3/lib/b.html
index dc9e034ac24d142ae1d4fe0abc63707ec6e420f7..6d94044d8a0c8a1eeb9d0948f93faf7017825e7b 100644
--- a/pkg/polymer/example/canonicalization3/lib/b.html
+++ b/pkg/polymer/e2e_test/bad_import3/lib/b.html
@@ -3,4 +3,9 @@ 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.
 -->
-<script type='application/dart;component=1' src='b.dart'></script>
+<!--
+Because this file is under lib/, this URL is broken. It should be either
+'a.html' or '../../packages/bad_import3/a.html'.
+ -->
+<link rel="import" href="broken_packages/bad_import3/a.html">
+