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

pkg/code_transformers/lib/assets.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.
 
 /// Common methods used by transfomers for dealing with asset IDs.
 library code_transformers.assets;
 
 import 'dart:math' show min, max;
 
 import 'package:barback/barback.dart';
@@ skipping 46 matching lines @@
   var assetsIndex = segments.indexOf('assets');
   var index = (packagesIndex >= 0 && assetsIndex >= 0)
       ? min(packagesIndex, assetsIndex)
       : max(packagesIndex, assetsIndex);
   if (index > -1) {
     if (entryFolder) {
       // URLs of the form "packages/foo/bar" seen under entry folders (like
       // web/, test/, example/, etc) are resolved as an asset in another
       // package. 'packages' can be used anywhere, there is no need to walk up
       // where the entrypoint file was.
+      // TODO(sigmund): this needs to change: Only resolve when index == 1 &&
+      // topFolder == segment[0], otherwise give a warning (dartbug.com/17596).
       return _extractOtherPackageId(index, segments, logger, span);
     } else if (index == 1 && segments[0] == '..') {
       // Relative URLs of the form "../../packages/foo/bar" in an asset under
       // lib/ or asset/ are also resolved as an asset in another package, but we
       // check that the relative path goes all the way out where the packages
       // folder lives (otherwise the app would not work in Dartium). Since
       // [targetPath] has been normalized, "packages" or "assets" should be at
       // index 1.
       return _extractOtherPackageId(1, segments, logger, span);
     } else {
@@ skipping 21 matching lines @@
   if (prefix != 'packages' && prefix != 'assets') return null;
   var folder = prefix == 'packages' ? 'lib' : 'asset';
   if (segments.length < index + 3) {
     logger.warning("incomplete $prefix/ path. It should have at least 3 "
         "segments $prefix/name/path-from-name's-$folder-dir", span: span);
     return null;
   }
   return new AssetId(segments[index + 1],
       path.url.join(folder, path.url.joinAll(segments.sublist(index + 2))));
 }