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

pkg/polymer/example/canonicalization3/lib/c.dart

Index: pkg/polymer/example/canonicalization3/lib/c.dart
diff --git a/pkg/polymer/example/canonicalization3/lib/c.dart b/pkg/polymer/example/canonicalization3/lib/c.dart
deleted file mode 100644
index 362f3e3d642f2e8c969c79de78dcc51bb95c3803..0000000000000000000000000000000000000000
--- a/pkg/polymer/example/canonicalization3/lib/c.dart
+++ /dev/null
@@ -1,7 +0,0 @@
-// 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.
-
-library canonicalization.c;
-
-int c = 0;