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

pkg/polymer/example/canonicalization2/lib/a.dart

Index: pkg/polymer/example/canonicalization2/lib/a.dart
diff --git a/pkg/polymer/example/canonicalization2/lib/a.dart b/pkg/polymer/example/canonicalization2/lib/a.dart
deleted file mode 100644
index dfbe3cae43697d624ce34f47d216e2f2010ccd94..0000000000000000000000000000000000000000
--- a/pkg/polymer/example/canonicalization2/lib/a.dart
+++ /dev/null
@@ -1,16 +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.a;
-
-import 'package:polymer/polymer.dart';
-import 'package:canonicalization/c.dart';
-import 'd.dart';
-
-int a = 0;
-@initMethod initA() {
-  a++;
-  c++;
-  d++;
-}